EP0025946B1 - Elément chauffant pour cathode à chauffage indirect - Google Patents

Elément chauffant pour cathode à chauffage indirect Download PDF

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Publication number
EP0025946B1
EP0025946B1 EP80105443A EP80105443A EP0025946B1 EP 0025946 B1 EP0025946 B1 EP 0025946B1 EP 80105443 A EP80105443 A EP 80105443A EP 80105443 A EP80105443 A EP 80105443A EP 0025946 B1 EP0025946 B1 EP 0025946B1
Authority
EP
European Patent Office
Prior art keywords
heating element
cap
heating
adjacent
distant
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
Application number
EP80105443A
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German (de)
English (en)
Other versions
EP0025946A1 (fr
Inventor
Eberhard Weiss
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.)
Nokia Deutschland GmbH
Original Assignee
International Standard Electric Corp
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 International Standard Electric Corp filed Critical International Standard Electric Corp
Publication of EP0025946A1 publication Critical patent/EP0025946A1/fr
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Expired legal-status Critical Current

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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
    • H01J1/22—Heaters

Definitions

  • the invention relates to a heating element for an indirectly heated cathode, which is inserted into a cathode tube, which is closed with a cap carrying the emitting layer, and which consists of a heating wire coil covered with an insulating layer, part of the heating element being adjacent to the cap and the other being further away from it is.
  • heating elements are known (DE-A 1564 462).
  • the part of the heating wire helix adjacent to the cap can either be M-shaped or a double helix.
  • Cathodes with a shorter heating time are also known (DE-A 2313911).
  • a cathode consisting of a cathode tube sealed with a cap carrying the emitting layer, into which a heating coil (heating element) covered with an insulating layer is inserted
  • various measures have been taken to reduce the heating-up time. These measures aim in particular to achieve a temperature distribution which has its maximum value on the cathode cap, which decreases with increasing distance from the cathode cap.
  • the user requests that a picture be obtained shortly after the device is switched on. This means that the cathode of the picture tube has to be heated up very quickly.
  • the object on which the invention is based is therefore to create a rapid heating cathode in which the heating element enclosed by the cathode tube and the cathode cap is designed in such a way that it generates as much heat as possible as quickly as possible during a short period of time in the heating phase.
  • the part of the heating element adjacent to the cap has a smaller heat capacity per unit length than the part farther away, the part adjacent to the cap consisting of at least two partial areas, between which at least one removed part with a larger heat capacity per unit length is arranged.
  • heating wire coil of the heating element runs more densely in the part adjacent to the cap than in the part further away, the part adjacent to the cap consisting of at least two partial regions, between which at least one part farther away with less density Heating wire coil is arranged.
  • the part adjacent to the cathode cap heats up very quickly for a short time (e.g. for 1-2 seconds) and has an excessive temperature during this time.
  • a short time e.g. for 1-2 seconds
  • the reason for this is that the part adjacent to the cap experiences a brief overheating because the tungsten wire of the heating element has a 1.2 to 1.5 times higher resistance during the sudden heating than in the operating state about 10 seconds later.
  • the heating output during this period is about 1.5 times higher than a few seconds later.
  • heating elements according to the invention practically do not differ in their electrical connection values and in their external mechanical dimensions from known heating elements, they can be exchanged for known heating elements without any change in the cathode and heating element fastening means. To produce heating elements according to the invention, however, no new devices are required, but only minor changes in the process sequence.
  • FIG. 1 a shows a front view and FIG. 1 b a side view of an embodiment of the heating element 1 according to the invention, which is inserted into a cathode tube 3 closed with a cap 2.
  • the part of the heating element 1 which is adjacent to the cap 2 is designated by 4, the part located at a distance by 5 B and 5 z .
  • the type of heating element shown is a so-called M-heating element. It consists of the tongue and the legs of the M. Therefore, the more distant part of the filament was designated 5 z and 5 B.
  • the invention is applicable regardless of the type of heating element used. It is only essential that the heating element has a length such that part of the heating element is adjacent to the cathode cap and another part of the heating element is further removed.
  • the invention can therefore also be implemented on a heating element designed as a double spiral.
  • the heating elements consist of filaments that are covered with an insulating layer.
  • the heating wire coil 6 can only be seen at the points where it is not covered. At these points, the filament is uncoiled so that it can be better attached to heating element fasteners.
  • the insulating layer in the part 4 adjacent to the cap is thinner than in the distant part 5 B , 5 z .
  • the oxide covering has a mass of approximately 0.25 mg / mm heating wire helix length. 1 has a mass of about 0.18 mg / mm in the adjacent part and a mass of about 0.36 mg / mm filament length in the distant part.
  • a known heating element lights up with dark red heat after 2 seconds, which corresponds to a temperature of approx. 600 ° C. After 4 seconds the heating element has reached its final temperature of approx. 850 ° C.
  • the heating element according to the invention already shines with bright red glow in the neighboring part 4 after 2 seconds, since only a small amount of oxide is to be heated here. In the distant part with a stronger oxide covering, that is to say a higher heat capacity, the heating element according to the invention only reaches dark red heat after about 3 seconds.
  • the different heating times of the two parts are determined not only by the different heat capacities but also very significantly by the temperature-dependent electrical resistance of the heating wire coil, usually a tungsten heating wire coil.
  • the specific resistance of the tungsten is 5.5 10-8 Qm at 20 ° C. If the specific resistance is set to one at 20 ° C, it is three at 430 ° C, four at 630 ° C and five at 820 ° C. In a known heating element that reaches about 600 ° C after 2 seconds, the specific resistance is about four times as large as at 20 ° C. In the heating element according to the invention, the resistivity in the colder, distant part is about three times as great as at 20 ° C. in the hotter, neighboring part. The resistance over the entire length of the heating element, and thus the flowing current, is approximately the same in both cases. The heating power is calculated from the product of the resistance and the square of the current. Since the current remains almost unchanged, but the resistance in the adjacent part of the heating element according to the invention is higher than in the known heating element, the heating power in the heating element according to the invention is also greater in the adjacent part.
  • the different heat capacities can also be achieved by applying a porous oxide layer in the adjacent part and a compact oxide layer in the distant part.
  • FIG. 2 shows another embodiment of the heating element 7.
  • the oxide layer covering the heating wire coil 6 is only indicated by dashed lines here.
  • the heating wire coil is only slightly coiled in the distant part 8 B , 8 z of the heating element, but tightly coiled in the adjacent part 9.
  • the indices B and Z have the same meaning as explained in the description of FIG. 1.
  • the heat effects are very similar to those explained in the description of FIG. 1. Because of the tight winding in the neighboring part, it heats up faster than the distant part that is further away. Due to the faster warming, the resistance rises sharply, which further supports the warming.
  • the total wire length is again chosen so that the same current results for the same heating voltage for a known heating element and the heating element according to the invention. After the temperature differences have been equalized, there is hardly any difference in the temperature distribution between a heating element according to the invention and a known heating element. The rapid heating of the adjacent part, however, considerably reduces the heating time of the cathode. While 90% of the cathode current that is reached in thermal equilibrium flows after about 4.5 seconds in known heating elements, this is reached after about 3.5 seconds in the heating element according to the invention.
  • Inventive heating elements may be prepared as follows: A in M-shape or egg - ner other selected curved shape heating coil is immersed in an electrophoresis bath, are deposited to about 0.18 mg / mm of oxide.
  • the filament is then pulled out of the electrophoresis bath and immersed in a washing bath to such an extent that the oxide covering is washed off in the adjacent part.
  • the heating wire coil is immersed again in the electrophoresis bath and 0.18 mg / mm oxide are deposited again. Further treatment is carried out as usual. This method gives the adjacent part a thin and the distant part of the heating element a thick oxide layer
  • the method can be modified insofar as the voltage is increased so much on the second immersion in the electrophoresis bath that electrolysis occurs at the same time.
  • the second oxide layer becomes porous and thus has an even lower heat capacity than the compactly applied layer.
  • a heating element according to FIG. 2 with a heating wire coil with different densities can be produced, as will be described with the aid of FIG. 3.
  • a tungsten wire is wound from molybdenum of 0.175 mm diameter, with 42 turns / cm over 7.2 mm length in part 8 z and 4.1 mm length in part 8 3 , as well as with 90 turns / cm each with 4, 2 mm length in part 9.
  • the core wire with the coiled heating wire is etched out in an acid bath as usual. Covering with an oxide layer can be done in a conventional manner or as described in the previous paragraphs.
  • the length of the heating element in the adjacent part is approximately one third of the total length.

Landscapes

  • Resistance Heating (AREA)
  • Solid Thermionic Cathode (AREA)
  • Electrodes For Cathode-Ray Tubes (AREA)

Claims (8)

1. Elément chauffant destiné à une cathode à chauffage indirect, inséré dans un tube de cathode fermé par un capuchon revêtu d'une couche émettrice, et composé d'une spirale de filament chauffant recouverte d'une couche isolante, une partie dudit élément chauffant étant voisine du capuchon tandis que l'autre en est plus éloignée, caractérisé en ce que la partie (4) de l'élément chauffant (1) voisine du capuchon présente une capacité thermique par unité de longueur plus petite que la partie éloignée (5s, 5z), ladite partie (4) voisine du capuchon étant constituée d'au moins deux segments entre lesquels est placée une partie éloignée (5z) possédant une plus grande capacité thermique par unité de longueur.
2. Elément chauffant destiné à une cathode à chauffage indirect, inséré dans un tube de cathode fermé par un capuchon revêtu d'une couche émettrice, et composé d'une spirale de filament chauffant recouverte d'une couche isolante, une partie dudit élément chauffant étant voisine du capuchon tandis que l'autre en est plus éloignée, caractérisé en ce que la spirale de filament chauffant (6) de l'élément chauffant (7) est plus serrée dans la partie voisine du capuchon (9) que dans la partie qui en est éloignée (8B, 8z), la partie voisine du capuchon (8B) étant composée d'au moins deux segments entre lesquels est placée au moins une partie plus éloignée (8z) dont la spirale de filament chauffant est moins serrée.
3. Elément chauffant conforme aux revendications 1 ou 2, caractérisé en ce que la spirale de filament chauffant (6) est revêtue d'une couche isolante plus mince dans la partie (4) voisine du capuchon (2) que dans la partie plus éloignée (5B, 5z).
4. Elément chauffant conforme aux revendications 1 ou 2, caractérisé en ce que la spirale de filament chauffant (6) est revêtue d'une couche isolante poreuse dans la partie (4) voisine du capuchon (3) et d'une couche isolante compacte dans la partie plus éloignée (5z, 5B).
5. Elément chauffant conforme aux revendications 1 ou 2, caractérisé en ce que la spirale de filament chauffant (6) est revêtue d'une couche compacte dans la partie éloignée (5z, 5B) et en ce qu'une couche poreuse est appliquée sur toute la longueur de la spirale de filament chauffant (1).
6. Elément chauffant conforme à l'une des revendications 1 à 5, caractérisé en ce que la spirale de filament chauffant (6) est pliée en forme de M.
7. Elément chauffant conforme à l'une des revendications 1 à 5, caractérisé en ce que la spirale de filament chauffant (6) présente la forme d'une double spirale.
8. Elément chauffant conforme à l'une des revendications 1 à 7, caractérisé en ce que la longueur de la partie (4, 9) voisine du capuchon (3) est égale à environ 1/3 de la longueur totale de la spirale de filament chauffant (6).
EP80105443A 1979-09-21 1980-09-12 Elément chauffant pour cathode à chauffage indirect Expired EP0025946B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE2938248 1979-09-21
DE19792938248 DE2938248A1 (de) 1979-09-21 1979-09-21 Heizelement fuer eine indirekt geheizte kathode

Publications (2)

Publication Number Publication Date
EP0025946A1 EP0025946A1 (fr) 1981-04-01
EP0025946B1 true EP0025946B1 (fr) 1985-02-06

Family

ID=6081482

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Application Number Title Priority Date Filing Date
EP80105443A Expired EP0025946B1 (fr) 1979-09-21 1980-09-12 Elément chauffant pour cathode à chauffage indirect

Country Status (4)

Country Link
US (1) US4355259A (fr)
EP (1) EP0025946B1 (fr)
JP (1) JPS56103842A (fr)
DE (1) DE2938248A1 (fr)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3029853C2 (de) * 1980-08-07 1982-08-26 Standard Elektrik Lorenz Ag, 7000 Stuttgart Indirekt durch Elektronenstoß geheizte Wehneltkathode
JPS58100329A (ja) * 1981-12-11 1983-06-15 Toshiba Corp 電子管用陰極構体
US4760306A (en) * 1983-06-10 1988-07-26 The United States Of America As Represented By The United States Department Of Energy Electron emitting filaments for electron discharge devices
US4939411A (en) * 1986-11-19 1990-07-03 North American Philips Corporation Composite vacuum evaporation coil
DE19828158C1 (de) * 1998-06-24 1999-11-25 Siemens Ag Indirekt geheizte Kathode, insbesondere für Röntgenröhren
US6690103B1 (en) 1999-07-21 2004-02-10 Alan K. Uke Incandescent light bulb with variable pitch coiled filament
US7009329B2 (en) 2003-08-20 2006-03-07 Hewlett-Packard Development Company, L.P. Thermally optimized cold cathode heater
JP2010225420A (ja) * 2009-03-24 2010-10-07 Stanley Electric Co Ltd 熱陰極蛍光ランプおよび蛍光ランプ用電極

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1858676A (en) * 1928-06-04 1932-05-17 Frederick S Mccullough Cathode
US2041904A (en) * 1931-04-04 1936-05-26 Nat Union Radio Corp Grid construction
US2917650A (en) * 1955-06-29 1959-12-15 Hyperion Sa Electrode for discharge tubes
US3255375A (en) * 1961-11-29 1966-06-07 Varian Associates Electrical heating device
NL288858A (fr) * 1962-09-11
NL6513665A (fr) * 1965-10-22 1967-04-24
DE2313911B2 (de) * 1973-03-20 1975-09-25 Standard Elektrik Lorenz Ag, 7000 Stuttgart Schnell anheizende Kathode für Kathodenstrahlröhren
DE2317446C3 (de) * 1973-04-06 1983-11-10 Standard Elektrik Lorenz Ag, 7000 Stuttgart Verfahren zum Herstellen eines Heizelementes für eine indirekt geheizte Kathode
US3883767A (en) * 1974-02-08 1975-05-13 Gte Sylvania Inc Heater for fast warmup cathode
JPS5427230B2 (fr) * 1974-10-30 1979-09-08

Also Published As

Publication number Publication date
EP0025946A1 (fr) 1981-04-01
US4355259A (en) 1982-10-19
DE2938248A1 (de) 1981-03-26
JPS56103842A (en) 1981-08-19

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