EP0298558A1 - Méthode pour fabriquer une cathode au scandate - Google Patents

Méthode pour fabriquer une cathode au scandate Download PDF

Info

Publication number
EP0298558A1
EP0298558A1 EP88201392A EP88201392A EP0298558A1 EP 0298558 A1 EP0298558 A1 EP 0298558A1 EP 88201392 A EP88201392 A EP 88201392A EP 88201392 A EP88201392 A EP 88201392A EP 0298558 A1 EP0298558 A1 EP 0298558A1
Authority
EP
European Patent Office
Prior art keywords
cathode
scandium
approximately
hydride
manufacturing
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.)
Granted
Application number
EP88201392A
Other languages
German (de)
English (en)
Other versions
EP0298558B1 (fr
Inventor
Johannes Van Esdonk
Jan Hasker
Josef Johannes Van Lith
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.)
Koninklijke Philips NV
Original Assignee
Philips Gloeilampenfabrieken NV
Koninklijke Philips Electronics NV
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
Application filed by Philips Gloeilampenfabrieken NV, Koninklijke Philips Electronics NV filed Critical Philips Gloeilampenfabrieken NV
Publication of EP0298558A1 publication Critical patent/EP0298558A1/fr
Application granted granted Critical
Publication of EP0298558B1 publication Critical patent/EP0298558B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

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
    • 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
    • H01J9/042—Manufacture, activation of the emissive part
    • H01J9/047—Cathodes having impregnated bodies
    • 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

Definitions

  • the invention relates to a method of manufacturing a dispenser cathode comprising a barium compound for dispensing barium to an emissive surface of a porous cathode body substantially comprising a metal melting at a high temperature.
  • the invention also relates to a dispenser cathode manufactured by means of such a method and to an electron tube provided with such a cathode.
  • a characteristic feature of dispenser cathodes is that there is a functional separation between the electron emissive surface on the one hand and a store of the emitter material for realizing a sufficiently low work function on the emissive surface on the other hand.
  • the emitter material is present in the pores of the porous metal cathode body.
  • European Patent Specification No. 0,091,161 describes how such cathodes can be improved on sensitivity to and recovery after ion bombardment by compressing the cathode body (notably the top layer) from a mixture of tungsten powder and scandium oxide and by subsequently sintering it.
  • the compressing operation is generally performed in two steps. Firstly, the tungsten portion of the cathode body is slightly pre­compressed. Subsequently, the top layer powder is evenly distributed over a surface of the tungsten portion whereafter the definitive compressing operation is performed.
  • a method according to the invention is characterized in that the cathode body is compressed from a quantity of metal powder which is mixed with scandium or scandium hydride whereafter the body is sintered and the cathode is provided with emitter material.
  • the quantity of scandium or scandium hydride in the quantity of metal powder is preferably 0.3-0.7% by weight.
  • this sintering operation is preferably performed at a temperature which is lower than the melting point of scandium (1539°C).
  • the sintering temperature must be chosen to be as high as possible in order to obtain a sufficiently robust cathode body.
  • a preferred embodiment of a method according to the invention is therefore characterized in that the sintering temperature is between 1430°C and 1500°C.
  • Figure 1 is a longitudinal cross-section of a cathode according to the invention.
  • the cathode body 1 is compressed from a mixture of tungsten powder and approximately 0.5% by weight of scandium or scandium-hydride. After compressing at a pressure of approximately 3.5 atmosphere and sintering in hydrogen for approximately one hour at 1450°, the cathode body of scandium and tungsten has a porosity of approximately 20%.
  • the cathode body 1 now has, for example, a thickness of 0.5 mm and a diameter of approximately 1.8 mm.
  • the cathode body 1 is impregnated in a hydrogen atmosphere with barium calcium aluminate (for example, 5BaO; 2Al2O3; 3CaO or 4BaO; 1Al2O3; 1CaO), compressed in a holder 2 and welded onto the cathode shank 3.
  • barium calcium aluminate for example, 5BaO; 2Al2O3; 3CaO or 4BaO; 1Al2O3; 1CaO
  • the cathode shank 3 accommodates a coiled cathode filament 4 comprising a helically wound metal core 5 and an aluminium oxide insulating layer 6.
  • the emission of the emissive surface 7 of such a cathode was approximately 100 A/cm2 at 950°C obtained at a pulse load at 1000 V in a diode with a cathode-anode distance of 0.3 mm.
  • Such an emission is comparable to that of a cathode with a top layer of tungsten and scandium oxide as described in European Patent Application No. 0,178,716 (PHN 11,169) which is more difficult to manufacture.
  • the recovery after ion bombardment was comparable to that of the cathode described in that Application with a cathode body sintered at approximately 1900°C (approximately 65%). In a cathode according to the invention, sintered at 1500°C this recovery was poorer and was approximately 58%.
  • the impregnant absorption was approximately 4.5%.
  • this absorption decreased to approximately 2% which shortens the life time of the cathode.
  • the quantity of absorbed impregnant is sufficient; the recovery after ion bombardment did not show any significant change in this range.
  • a cylinder 20 with an emissive surface 21 in which a heating element is provided and which is shown in an elevational view in Figure 2 can also be turned from a tungsten body compressed in accordance with the method as described hereinbefore.
  • the cathodes according to the invention may be used in electron tubes such as, for example magnetrons, transmitter tubes, etc., but also in cathode-ray tubes for e.g. television applications and electron microscopy.

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Solid Thermionic Cathode (AREA)
  • Powder Metallurgy (AREA)
EP88201392A 1987-07-06 1988-07-04 Méthode pour fabriquer une cathode au scandate Expired - Lifetime EP0298558B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL8701583A NL8701583A (nl) 1987-07-06 1987-07-06 Scandaatkathode.
NL8701583 1987-07-06

Publications (2)

Publication Number Publication Date
EP0298558A1 true EP0298558A1 (fr) 1989-01-11
EP0298558B1 EP0298558B1 (fr) 1994-05-25

Family

ID=19850259

Family Applications (1)

Application Number Title Priority Date Filing Date
EP88201392A Expired - Lifetime EP0298558B1 (fr) 1987-07-06 1988-07-04 Méthode pour fabriquer une cathode au scandate

Country Status (5)

Country Link
EP (1) EP0298558B1 (fr)
JP (1) JP2685232B2 (fr)
KR (1) KR890002949A (fr)
DE (1) DE3889696T2 (fr)
NL (1) NL8701583A (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5264757A (en) * 1989-11-13 1993-11-23 U.S. Philips Corporation Scandate cathode and methods of making it
EP0651419A1 (fr) * 1993-10-28 1995-05-03 Koninklijke Philips Electronics N.V. Cathode à réserve et méthode de fabrication
BE1007677A3 (nl) * 1993-10-28 1995-09-12 Philips Electronics Nv Werkwijze voor het vervaardigen van een naleveringskathode.
BE1007676A3 (nl) * 1993-10-28 1995-09-12 Philips Electronics Nv Werkwijze voor het vervaardigen van een naleveringskathode.
WO1995025337A1 (fr) * 1994-03-15 1995-09-21 Philips Electronics N.V. Cathode a diffusion et procede de fabrication de cette derniere

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6281626B1 (en) * 1998-03-24 2001-08-28 Casio Computer Co., Ltd. Cold emission electrode method of manufacturing the same and display device using the same

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4007393A (en) * 1975-02-21 1977-02-08 U.S. Philips Corporation Barium-aluminum-scandate dispenser cathode
EP0091161A1 (fr) * 1982-04-01 1983-10-12 Koninklijke Philips Electronics N.V. Procédé de fabrication d'une cathode à réserve et cathode à réserve fabriquée selon ce procédé
EP0178716A1 (fr) * 1984-10-05 1986-04-23 Koninklijke Philips Electronics N.V. Procédé de fabrication d'une cathode à réserve comprenant du scandate et cathode à réserve comprenant du scandate fabriquée suivant ce procédé
EP0179513A1 (fr) * 1984-10-05 1986-04-30 Koninklijke Philips Electronics N.V. Procédé de fabrication d'une cathode à réserve comprenant du scandate et cathode à réserve fabriquée par ce procédé

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS58154131A (ja) * 1982-03-10 1983-09-13 Hitachi Ltd 含浸形陰極
JPS63254636A (ja) * 1987-04-10 1988-10-21 Hitachi Ltd 含浸形陰極

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4007393A (en) * 1975-02-21 1977-02-08 U.S. Philips Corporation Barium-aluminum-scandate dispenser cathode
EP0091161A1 (fr) * 1982-04-01 1983-10-12 Koninklijke Philips Electronics N.V. Procédé de fabrication d'une cathode à réserve et cathode à réserve fabriquée selon ce procédé
EP0178716A1 (fr) * 1984-10-05 1986-04-23 Koninklijke Philips Electronics N.V. Procédé de fabrication d'une cathode à réserve comprenant du scandate et cathode à réserve comprenant du scandate fabriquée suivant ce procédé
EP0179513A1 (fr) * 1984-10-05 1986-04-30 Koninklijke Philips Electronics N.V. Procédé de fabrication d'une cathode à réserve comprenant du scandate et cathode à réserve fabriquée par ce procédé

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN, vol. 8, no. 190 (E-263)[1627], 31st August 1984; & JP-A-59 79 934 (HITACHI SEISAKUSHO K.K.) 09-05-1984 *

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5264757A (en) * 1989-11-13 1993-11-23 U.S. Philips Corporation Scandate cathode and methods of making it
US5314364A (en) * 1989-11-13 1994-05-24 U.S. Philips Corporation Scandate cathode and methods of making it
CN1036165C (zh) * 1989-11-13 1997-10-15 菲利浦光灯制造公司 钪酸盐阴极
EP0651419A1 (fr) * 1993-10-28 1995-05-03 Koninklijke Philips Electronics N.V. Cathode à réserve et méthode de fabrication
BE1007677A3 (nl) * 1993-10-28 1995-09-12 Philips Electronics Nv Werkwijze voor het vervaardigen van een naleveringskathode.
BE1007676A3 (nl) * 1993-10-28 1995-09-12 Philips Electronics Nv Werkwijze voor het vervaardigen van een naleveringskathode.
US5666022A (en) * 1993-10-28 1997-09-09 U.S. Philips Corporation Dispenser cathode and method of manufacturing a dispenser cathode
WO1995025337A1 (fr) * 1994-03-15 1995-09-21 Philips Electronics N.V. Cathode a diffusion et procede de fabrication de cette derniere

Also Published As

Publication number Publication date
DE3889696T2 (de) 1994-12-08
KR890002949A (ko) 1989-04-12
JPH01163941A (ja) 1989-06-28
JP2685232B2 (ja) 1997-12-03
DE3889696D1 (de) 1994-06-30
NL8701583A (nl) 1989-02-01
EP0298558B1 (fr) 1994-05-25

Similar Documents

Publication Publication Date Title
US4625142A (en) Methods of manufacturing a dispenser cathode and dispenser cathode manufactured according to the method
EP0179513B1 (fr) Procédé de fabrication d'une cathode à réserve comprenant du scandate et cathode à réserve fabriquée par ce procédé
EP0200276B1 (fr) Procédé de fabrication d'une cathode à réserve et utilisation de ce procédé
GB2116356A (en) Impregnated cathode
US4873052A (en) Method of manufacturing a scandate dispenser cathode and scandate dispenser cathode manufactured according to the method
EP0298558A1 (fr) Méthode pour fabriquer une cathode au scandate
EP0428206B1 (fr) Cathode à scandate
EP0390269B1 (fr) Cathode à scandate
US4982133A (en) Dispenser cathode and manufacturing method therefor
US5261845A (en) Scandate cathode
US3760218A (en) Thermionic cathode
KR920004552B1 (ko) 디스펜서 음극
KR20000009399A (ko) 음극선관용 음극 및 그 제조방법
EP0930633A1 (fr) Cathode à chauffage indirect et tube à rayons cathodiques comportant une telle cathode
JPH11288689A (ja) 放電管用の電極
JP4300042B2 (ja) 放電ランプ用陰極の製造方法
JPH0118537B2 (fr)
KR920004551B1 (ko) 디스펜서 음극
Yamamoto Recent development of cathodes used for cathode ray tubes
JP2001006607A (ja) 放電管および放電管用陰極の製造方法
JP2004241249A (ja) 含浸型陰極およびその製造方法
JPH05234502A (ja) 放電ランプ用電極の製造方法

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): DE FR GB IT NL

17P Request for examination filed

Effective date: 19890707

17Q First examination report despatched

Effective date: 19920319

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): DE FR GB IT NL

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: IT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT;WARNING: LAPSES OF ITALIAN PATENTS WITH EFFECTIVE DATE BEFORE 2007 MAY HAVE OCCURRED AT ANY TIME BEFORE 2007. THE CORRECT EFFECTIVE DATE MAY BE DIFFERENT FROM THE ONE RECORDED.

Effective date: 19940525

Ref country code: NL

Effective date: 19940525

REF Corresponds to:

Ref document number: 3889696

Country of ref document: DE

Date of ref document: 19940630

ET Fr: translation filed
NLV1 Nl: lapsed or annulled due to failure to fulfill the requirements of art. 29p and 29m of the patents act
PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
REG Reference to a national code

Ref country code: FR

Ref legal event code: CD

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 19970701

Year of fee payment: 10

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 19980704

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 19980716

Year of fee payment: 11

REG Reference to a national code

Ref country code: FR

Ref legal event code: CD

GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 19980704

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Free format text: THE PATENT HAS BEEN ANNULLED BY A DECISION OF A NATIONAL AUTHORITY

Effective date: 19990731

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 20000918

Year of fee payment: 13

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20020501