EP1292963A1 - Cathode with optimised thermal efficiency - Google Patents
Cathode with optimised thermal efficiencyInfo
- Publication number
- EP1292963A1 EP1292963A1 EP01943582A EP01943582A EP1292963A1 EP 1292963 A1 EP1292963 A1 EP 1292963A1 EP 01943582 A EP01943582 A EP 01943582A EP 01943582 A EP01943582 A EP 01943582A EP 1292963 A1 EP1292963 A1 EP 1292963A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- cathode
- skirt
- cap
- filament
- emissive
- 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.)
- Withdrawn
Links
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
- H01J29/04—Cathodes
-
- 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
Definitions
- the invention relates to a cathode for electron guns of cathode ray tubes, the structure of which is improved with a view to reducing the length of the cathode and optimizing the thermal efficiency of said cathode.
- the invention finds its application as well for cathode ray tube of monochrome type as for a tube of color type.
- a cathode for an electron gun of cathode ray tube generally comprises a cap on which is deposited a material intended to emit an electron beam, a cathode skirt of cylindrical shape forming with the cap a unitary assembly, a heating filament inserted in the skirt, the filament generally comprising a spiral part placed near the cap and connection tabs to the electrical supply circuit, this connection being effected through the orifice of the skirt located opposite the cap; the legs of the filaments are welded to rigid stirrups secured to the structure of the barrel through electrically non-conductive parts, for example made of glass.
- the cathode itself is held in place in the lower part of the barrel by means of a sleeve joined together, for example by welding, at the end of the skirt opposite the cap.
- Such a structure is for example described in American patent US Pat. No. 4,403,169.
- patent US5013965 proposes using a cylindrical cathode skirt having the particularity of being closed at the end opposite the cap. This configuration improves the thermal efficiency of known cathodes by thermal conduction from the skirt to the emissive part, but insufficiently and in particular does not significantly accelerate the start-up time of the cathode, an important characteristic for quickly obtaining an image on a television screen.
- the cathode for electron gun of cathode ray tube provides these improvements by comprising: a part composed of emissive materials for generating an electron beam; a metal cap on which the emissive part is disposed; a heating filament, of spiral form disposed under the cap and terminated by connecting lugs, a skirt surrounding the spiral part of the filament and forming with the cap a closed space, characterized in that the internal surface of the rear part of the skirt opposite the cap has a shape adapted to reflect the heat energy of the filament towards the emissive part.
- FIG. 1 is a sectional view of a cathode according to the state of the art
- FIG. 2 is a sectional view of a first embodiment of the invention
- FIG. 3 illustrates a second embodiment of the invention
- FIG. 4 is a top view of a cathode according to the invention.
- FIG. 5 is a perspective view of the emissive part and the coiled filament of a cathode according to the invention.
- a cathode according to the state of the art as illustrated by FIG. 1, comprises an emissive part 1 in the form of a layer of emissive material for an oxide cathode or a pellet impregnated with emissive materials in the case of a so-called impregnated cathode.
- the emissive material is supported by a cathode cap 2, disposed at one end of a cylindrical skirt 3; the skirt 3 extends in a direction Z perpendicular to the emissive surface of 1; the skirt 3 is closed at its end 4 opposite the cap, so as to form a closed cylinder in which the filament 5 of the cathode is enclosed; the tabs of the filament pass through the cathode skirt thanks to orifices 9 made in the end 4 opposite the cap.
- the cathode is supported in the barrel structure by a sleeve 7 conventionally connected to the other parts of the electron gun.
- this type of structure has two major drawbacks: - its length along the main axis Z is significant and contributes to lengthening the length of the electron gun which incorporates it and consequently the depth of the tube equipped with such a gun ,
- the cathode according to the invention shown in a first embodiment according to FIG. 2, offers a length along the Z axis that is shortened compared to the prior art.
- FIG. 2 illustrates an embodiment in the case of an impregnated cathode but can be applied in the same way to an oxide cathode.
- the cathode comprises a cap 11 supporting a pellet 10 of porous materials impregnated with emissive materials.
- a metal skirt 14 is attached to the cap.
- the two connection lugs 15 of the filament 13 do not pass through the bottom of the skirt 14 but through its side wall through orifices or notches 19. These orifices or notches are preferably arranged near the cap 11, or else at the end of the skirt 14 closest to said cap.
- the cathode composed of its emissive part O, of the cap 11, of its skirt 14 and of the filament 13, is held in place by means of a support 17 electrically insulating, for example made of sintered glass, the mechanical connection between the support 17 and the cathode / filament assembly (10,11,13,14) is effected by a plurality of arms 12, welded to metal studs 16 included in the support insulator 17.
- These arms can for example be three in number, arranged at 120 ° from one another; they preferably extend in a plane substantially parallel to the surface of the support 17 and to the surface of the emissive part 10 of the cathode in order to reduce the axial length of the cathode. As illustrated in FIG.
- one of the arms 12 serves as an electrical connection to bring the cathode to an ad hoc potential thanks to a connector 18 connected to an electrical power source.
- the filament 13 has a coating which provides electrical isolation between, on the one hand the conductive core of the filament electrically connected to the legs 15, on the other hand the elements (10, 11, 12, 14, 16, 18) connected electrically between them. For example, this coating extends over the entire part of the filament contained in the space delimited by the cap 11 and the skirt 14, and also extends beyond the orifices 19.
- the two connection lugs 15 of the filament are used as the cathode support arm, said lugs being connected, for example by welding, to the studs 16 included in the insulating part 17.
- the two tabs of the filament can pass through the lateral part of the skirt 14, at 120 ° from one another, in a plane parallel to the surface of the emissive part 10.
- Mechanical stability is ensured by at least one arm 12, in this case disposed at 120 ° from the two lugs 15.
- the mounting of the cathode is carried out for example as follows:
- the filament 13 with its two legs extending at 120 ° from one another is disposed under the cap 11 on which an arm 12 is previously welded.
- the skirt 14 having on its periphery three notches 19 at 120 ° from one another, is assembled to the cap 11 so that the legs 15 and the arm 12 pass through said notches 19.
- the dimensions of the notches are adapted to dimensions of the legs 15 and of the arm 12 so as to make a tight adjustment in order to avoid any subsequent movement of these elements during operation.
- the skirt 14 is secured, for example by welding, to the cap 11
- the legs 15 and the arm 12 are secured, for example by welding, to the metal studs 16 included in the insulating support 17.
- the unitary module thus produced, allows to be inserted alone, or by three, in the lower part of an electron gun for monochrome or color cathode ray tubes.
- the first electrode of the barrel comprises means into which the cathode module is inserted in order to maintain facing the orifice of said grid and at the right distance from it, the emissive part of the cathode .
- the invention thus makes it possible to significantly reduce the axial length of the cathode, but also makes it possible to increase the thermal efficiency of the latter.
- the cathode structure according to the invention it is now possible to close the lower part, opposite the cap 11, and to use it as a thermal reflector by returning the radiant thermal energy directly to the emissive part of the cathode.
- the cup shape of the internal surface of the lower part of the skirt is adapted so as to carry out this function of reflector towards the zone of the cap 11 supporting the emissive part 10; thus the internal surface of the closed lower part of the skirt can have any concave shape adapted to perform this function; it can preferably have a conical or frustoconical shape which is easy to produce industrially, the angle at the top of the cone being chosen so that part of the heat which is not directly captured by the emissive part 10 either sent by radiation reflection to the area of the cap supporting the emissive part 10.
- the shape of the filament 13 is adapted so as to follow the shape of the internal surface of the skirt; thus, the head 20 of the filament has a space requirement in a plane parallel to the plane of the emissive surface of the cathode weaker than at its base located closer to said emissive part.
- the filament can for example be spiral on a cone, so as to increase the surface of the filament facing directly with the surface of the cap 11 located under the emissive part and to decrease its average distance from said surface.
- the use of the tabs 15 as a cathode support makes it possible, with respect to a structure according to the state of the art, to reduce the heat losses, on the one hand by radiation, and on the other hand by conduction in the elements of support of the cathode like the sleeve 7 of FIG. 1.
- the cathode structure according to the invention makes it possible both to reduce the size of the cathode and to improve its thermal efficiency
- the fact of having a filament closer to the emissive part with a lower part of the skirt in the form of a thermal reflector also makes it possible to improve by reducing the start-up time of the cathode, start-up time corresponding to the time which elapses between the application of the supply voltage of the filament and the obtaining of the electron current emitted by the cathode.
Abstract
Description
Claims
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR0007911A FR2810789A1 (en) | 2000-06-21 | 2000-06-21 | Cathode for electron gun includes reflective skirt beneath heating filament to direct heat energy on to emissive element |
FR0007911 | 2000-06-21 | ||
PCT/FR2001/001763 WO2001099140A1 (en) | 2000-06-21 | 2001-06-07 | Cathode with optimised thermal efficiency |
Publications (1)
Publication Number | Publication Date |
---|---|
EP1292963A1 true EP1292963A1 (en) | 2003-03-19 |
Family
ID=8851484
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP01943582A Withdrawn EP1292963A1 (en) | 2000-06-21 | 2001-06-07 | Cathode with optimised thermal efficiency |
Country Status (9)
Country | Link |
---|---|
US (1) | US6946781B2 (en) |
EP (1) | EP1292963A1 (en) |
JP (1) | JP2004514241A (en) |
KR (1) | KR20030011917A (en) |
CN (1) | CN1224997C (en) |
AU (1) | AU2001266126A1 (en) |
FR (1) | FR2810789A1 (en) |
MX (1) | MXPA02012357A (en) |
WO (1) | WO2001099140A1 (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2004221010A (en) * | 2003-01-17 | 2004-08-05 | Matsushita Electric Ind Co Ltd | Cathode structure, electron gun, and cathode-ray tube |
FR2871933A1 (en) * | 2004-06-21 | 2005-12-23 | Thomson Licensing Sa | LOW CONSUMPTION CATHODE STRUCTURE FOR CATHODE RAY TUBES |
CN111729212A (en) * | 2020-07-27 | 2020-10-02 | 上海联影医疗科技有限公司 | Cathode heater of microwave source, cathode and radiotherapy equipment |
Family Cites Families (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR1303636A (en) * | 1961-08-04 | 1962-09-14 | Electronique & Physique | Improvements to radiant electrical systems, in particular to flat cathodes or the like |
FR1422700A (en) * | 1965-01-26 | 1965-12-24 | Varian Associates | Thermionic cathode filament and method of manufacture |
US3566179A (en) * | 1968-06-20 | 1971-02-23 | American Microwave Inc | Cathode and heater constructions and mountings in electron discharge devices |
JPS5488059A (en) * | 1977-12-26 | 1979-07-12 | Hitachi Ltd | Thermion emission cathode |
NL8002343A (en) * | 1980-04-23 | 1981-11-16 | Philips Nv | ELECTRON GUN AND CATHODE JET CONTAINING SUCH ELECTRON GUN. |
JPS60150536A (en) * | 1984-01-17 | 1985-08-08 | Hitachi Ltd | Thermionic-emission cathode |
FR2621735A1 (en) * | 1987-10-09 | 1989-04-14 | Thomson Csf | ROBUST OXIDE CATHODE FOR CATHODE RAY TUBE |
NL8802344A (en) * | 1988-09-22 | 1990-04-17 | Philips Nv | ELECTRON CANNON AND METHOD FOR MANUFACTURING AN ELECTRON CANNON. |
KR910007793B1 (en) * | 1988-11-02 | 1991-10-02 | 삼성전관 주식회사 | Cathode of crt and the method of making the same |
JP2607654B2 (en) * | 1988-12-16 | 1997-05-07 | 株式会社東芝 | Indirectly heated cathode structure and electron gun structure using the same |
KR910005832Y1 (en) * | 1989-07-13 | 1991-08-05 | 삼성전관 주식회사 | Cathode structure for electron gun |
WO1991003065A1 (en) * | 1989-08-18 | 1991-03-07 | Nikolai Fedorovich Osaulenko | Cathode heating unit for electron-ray devices |
KR930004222B1 (en) * | 1991-03-22 | 1993-05-21 | 주식회사 금성사 | Electron gun for crt |
US5444327A (en) * | 1993-06-30 | 1995-08-22 | Varian Associates, Inc. | Anisotropic pyrolytic graphite heater |
-
2000
- 2000-06-21 FR FR0007911A patent/FR2810789A1/en active Pending
-
2001
- 2001-06-07 KR KR1020027017418A patent/KR20030011917A/en not_active Application Discontinuation
- 2001-06-07 WO PCT/FR2001/001763 patent/WO2001099140A1/en not_active Application Discontinuation
- 2001-06-07 AU AU2001266126A patent/AU2001266126A1/en not_active Abandoned
- 2001-06-07 JP JP2002503898A patent/JP2004514241A/en not_active Withdrawn
- 2001-06-07 MX MXPA02012357A patent/MXPA02012357A/en active IP Right Grant
- 2001-06-07 EP EP01943582A patent/EP1292963A1/en not_active Withdrawn
- 2001-06-07 CN CNB018115748A patent/CN1224997C/en not_active Expired - Fee Related
- 2001-06-07 US US10/297,657 patent/US6946781B2/en not_active Expired - Fee Related
Non-Patent Citations (1)
Title |
---|
See references of WO0199140A1 * |
Also Published As
Publication number | Publication date |
---|---|
CN1224997C (en) | 2005-10-26 |
MXPA02012357A (en) | 2004-06-30 |
WO2001099140A1 (en) | 2001-12-27 |
AU2001266126A1 (en) | 2002-01-02 |
US6946781B2 (en) | 2005-09-20 |
CN1446369A (en) | 2003-10-01 |
KR20030011917A (en) | 2003-02-11 |
US20030164667A1 (en) | 2003-09-04 |
FR2810789A1 (en) | 2001-12-28 |
JP2004514241A (en) | 2004-05-13 |
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Legal Events
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PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
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Effective date: 20021216 |
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AX | Request for extension of the european patent |
Extension state: AL LT LV MK RO SI |
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RBV | Designated contracting states (corrected) |
Designated state(s): AT BE CH DE FR GB LI |
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17Q | First examination report despatched |
Effective date: 20050304 |
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RAP1 | Party data changed (applicant data changed or rights of an application transferred) |
Owner name: THOMSON LICENSING |
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STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
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18D | Application deemed to be withdrawn |
Effective date: 20080103 |