EP0073190B1 - Element chauffant electriquement resistif possedant une commande de la temperature - Google Patents

Element chauffant electriquement resistif possedant une commande de la temperature Download PDF

Info

Publication number
EP0073190B1
EP0073190B1 EP81901612A EP81901612A EP0073190B1 EP 0073190 B1 EP0073190 B1 EP 0073190B1 EP 81901612 A EP81901612 A EP 81901612A EP 81901612 A EP81901612 A EP 81901612A EP 0073190 B1 EP0073190 B1 EP 0073190B1
Authority
EP
European Patent Office
Prior art keywords
temperature
current
heating element
ferromagnetic
ferromagnetic material
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
EP81901612A
Other languages
German (de)
English (en)
Other versions
EP0073190A4 (fr
EP0073190A1 (fr
Inventor
Philip S. Carter
John F. Krumme
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.)
Metcal Inc
Original Assignee
Metcal Inc
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 Metcal Inc filed Critical Metcal Inc
Priority to AT81901612T priority Critical patent/ATE53737T1/de
Publication of EP0073190A1 publication Critical patent/EP0073190A1/fr
Publication of EP0073190A4 publication Critical patent/EP0073190A4/fr
Application granted granted Critical
Publication of EP0073190B1 publication Critical patent/EP0073190B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/10—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor
    • H05B3/12—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material

Definitions

  • Thermally regulated heating elements of a wide variety of types have existed for some time. Most often these elements have utilized some form of feedback control system in which the temperature produced is sensed and the source of electrical energization to the heating element is controlled either in a continuous, proportional or step-wise switching fashion to achieve more-or-less constant temperature. Utilizing a wide variety of thermal sensors and various control systems, these approaches continue to be successfully used in many applications.
  • a second situation in which the prior art feedback control systems are not adequate is where the heating element itself is so small as to make adequate monitoring of its temperature by a separate sensing means impractical.
  • a thermally dependent parameter of the heating element as a means of sensing its own temperature.
  • the resultant apparatus is complex and relatively expensive.
  • the electrical connection to the distal end of the blade is effected by means of an electrical conductor that is laid along the side of the blade and follows generally the profile of the cutting edge of the blade but some distance in from that edge, this conductor being electrically insulated from the blade along the whole of its length except at the distal end connection, whereby the blade of the scalpel and the electric conductor laid along side it are electrically connected in series.
  • US-A-4017344 describes electrical transmission cables in which the core conductor of the cable is coaxially surrounded by a thin layer of ferromagnetic material in electrical contact therewith. During manufacture, the temperature is raised to a value near the recrystallisation temperature of the ferromagnetic material, and the material thereafter cooled, while electrical current is passed through the core conductor, in order to orientate the magnetisation of the ferromagnetic layer circumferentially.
  • the principle object of the present invention is to provide a resistive heating element which employs the Curie temperature characteristics of ferromagnetic material for self-regulation of its temperature and in which significantly better auto-regulation of temperature is achieved than has been possible in any prior heater using Curie point characteristics.
  • a temperature autoregulating heater employing the Curie point characteristics of a ferromagnetic material such that over a range of temperatures rising toward the Curie temperature of the ferromagnetic material the heater exhibits a negative temperature coefficient of resistance, the heater comprising:
  • the declining magnetic permeability of the ferromagnetic surface layer markedly reduces the skin effect causing a migration or spreading of the current into the non-magnetic member of the heating element.
  • the resistance of the heating element declines sharply near the Curie temperature such that at constant current, the power dissipated by the heating element likewise declines.
  • any localized variations in thermal load on the heating element are automatically compensated, since the resistance of any axial portion of the heating element, however short, is a function of its temperature.
  • the high thermal conductivity of the non-magnetic member is a further aid in equalizing temperature over the extent of the heating element.
  • the heating element according to the present invention can provide accurate temperature regulation despite extremely small physical size.
  • the constant current R.F. source can be significantly cheaper than the complex feedback- controlled power supplies of the prior art.
  • Fig. 1 there is shown a simplified cylindrical heating element 1 connected in series circuit relationship with an R.F. source 3 and an on-off switch 5.
  • R.F. source 3 might provide high frequency alternating current power typically in the range from 8-20 MHz, for example, and might desirably include constant current regulation for reasons that will appear from what follows.
  • cylinders illustrated in Figs. 1, 2 and 4 of this application are plainly circular cylinders, it is to be understood that the use of the term "cylinder” in this application is by no means limited to the special case of circular cylinders; it is intended that this term encompass cylinders of any cross-sectional shape except where otherwise indicated.
  • electrical circuit arrangements illustrated all employ direct or ohmic connection to a source of alternating current electric power, it is to be understood thatthe invention is not so limited since the range of its application also includes those cases where the electric power source is electrically coupled to the heating element inductively or capacitively.
  • Heating element 1 is traversed along its major axis or length by a high frequency alternating current from R.F. source 3. The effect of this current is to cause 1 2 R heating or "Joule" heating. If, as suggested above, R.F. source 3 is provided with constant current regulation, then 1 2 is a constant and the power absorbed by heating element 1 from R.F. source 3 is proportional to the resistance R of element 1 between the points of connection to the external circuit.
  • heating element 1 has a composite structure in which an inner core or substrate 7, which might be made of copper or other non-magnetic, electrically and thermally conductive material is surrounded by or clad by a sheath or plating in the form of layer 9 which is made of a magnetic material such as a ferromagnetic alloy having a resistivity higher than the resistivity of the conductive material of core 7.
  • Fig. 2 the current density profile across the cross-section of a conductor carrying high frequency current is illustrated. If the conductor is in the form of a circular cylindrical conductor of radius r, then the current density profile has the general form, under conditions of relatively high frequency excitation, illustrated by characteristic 11 in Fig. 2, showing a marked increase in current density in the surface regions of conductor 1'.
  • characteristic 11 clearly illustrates the "skin effect" whereby alternating currents are concentrated more heavily in the surface regions of the conductor than in the interior volume thereof.
  • the high concentration of current at the surface region of the conductor is more pronounced the higher the frequency is.
  • the skin effect is dependent upon the magnetic permeability of the conductor: In a "thick" conductor having a planar surface and a thickness T, energized by an alternating current source connected to produce a current parallel to the surface, the current density under the influence of the skin effect can be shown to be an exponentially decreasing function of the distance from the surface of the conductor: where:
  • Fig. 2 The lower part of Fig. 2 is a graph of current density j across the diameter of conductor 1'.
  • current density profile 11 shows the expected high current density at the surface of conductor 1' tapering rapidly to a very low current in the interior of conductor 1'.
  • Profile 13 illustrates the current density for a temperature in the region of the Curie temperature of the ferromagnetic material of conductor 1': the characteristic shows a considerable lessening of the skin effect with only a moderate falling off of current away from the surfaces of conductor 1'.
  • Characteristic 15 is for a uniform ferromagnetic conductor such as, for example, the conductor 1' shown in Fig. 2, carrying a constant current I,. As shown, characteristic 15 exhibits a sharp drop in power absorbed from an R.F. energizing source such as R.F. source 3 in Fig. 1, as the Curie temperature T c is approached. Following this sharp drop in power, characteristic 15 levels off at a level labeled P min in Fig. 3.
  • Characteristic 16 in Fig. 3 shows a typical power versus temperature curve for a composite heating element such as element 1 in Fig. 1 in which a non-magnetic conductive core is surrounded by a ferromagnetic surface layer. Characteristic 16 also illustrates the very similar behavior of a hollow, cylindrical non-magnetic conductor which has been provided with a ferromagnetic layer on its inside surface, or indeed any composite conductor formed principally of a non-magnetic conductive member with a ferromagnetic surface layer according to the present invention. Although qualitatively the shape of characteristic 16 is similar to that for characteristic 15, it is to be noted that characteristic 16 descends more nearly vertically to a lower value of minimum power input.
  • a third characteristic 17 illustrates the effect of increasing the current carried by the composite heating element to a new value 1 2 which is greater than 1 1 , As illustrated, characteristic 17 shows the effect of such a current increase where 1 2 has been selected so as to produce the same level of minimum power P min as was obtained in the case of the characteristic for a uniform ferromagnetic conductor 15 operating at current 1 1 .
  • Load lines 19 and 21 are graphs of total power lost through conduction, convection, and radiation, shown as a function of temperature. As will be apparent to those skilled in the art, load line 19 is for a condition of greater thermal lossiness than load line 21. For example, line 19 might represent the thermal load when a fluid coolant is brought into contact with the heating element.
  • R(T) the resistance of the heating element
  • the consequent significant reduction in skin effect causes current, which flowed almost entirely in the surface layer of the heating element at low temperatures, to migrate or spread into the body of the heating element such that more and more current flows through the interior as temperature rises near T c . Since the available cross-section for current flow is thus increased and since most of the current is flowing in a highly conductive medium, resistance drops causing a corresponding drop in power consumption.
  • the composite heating element according to the present invention only a relatively thin surface layer of the heating element is formed of ferromagnetic material, while the remainder consists of a substrate member made of non-magnetic material having high electrical conductivity. Consequently, the decline in resistance and power consumption which is experienced with a purely ferromagnetic heating element is greatly increased by the use of a non-magnetic, highly conductive core.
  • the ratio ⁇ min / ⁇ max is sufficiently close to 1 such that to a good approximation, Since ⁇ l r max has values which fall in the range from 100-600 for commercially available magnetic materials, and further since pr m , " (the value above T c ) is approximately equal to 1, the ratio Rma/Rmln has a range of values for ferromagnetic materials from approximately ⁇ 100 to 600, or approximately 10 to 25.
  • this modest ratio of resistances can be vastly increased by selection of the relative cross-sectional areas and conductivities of the non-magnetic member and its ferromagnetic surface layer.
  • the temperature at which regulation will take place is also variable.
  • Fig. 4 there is shown a novel application of the present invention to form a heated conduit for the transmission of fluid such as, for example, crude oil over long distances while maintaining the fluid at a selected elevated temperature designed to minimize viscosity.
  • the conduit 23 of Fig. 4 comprises a hollow cylindrical core 25 which may be made of copper or a less expensive non-magnetic material, for example.
  • a ferromagnetic layer 27 Surrounding and immediately adjacent and in contact with the surface of core 25 is a ferromagnetic layer 27 which is in good thermal and electrical contact with core 25 substantially throughout its length.
  • An insulative layer 29 which might be made of a plastic chosen to withstand the environment in which conduit 23 will be used surrounds core 25 and layer 27, electrically and thermally separating them from an outer sheath 31 which might be a woven mesh of fine copper wires, or any other suitable conductive sheath material.
  • a source or R.F. current to energize conduit 23 would be connected between sheath 31 and core 25 and layer 27.
  • sheath 31 would be operated at ground potential in order to avoid accidental short circuits.
  • Fig. 5 is shown an additional application of the present invention to a soldering iron tip 33 of conical shape.
  • Tip 33 is comprised of an outer non-magnetic shell 35 which might be made of copper or molybdenum, for example, and which is in good thermal and electrical contact with an inner ferromagnetic shell 37, thus forming a composite self-regulating heating element in accordance with the present invention.
  • An inner conductive, non-magnetic stem 39 extends axially into conical shells 35 and 37 and may be joined to inner shell 37 as by spot welding, for example.
  • An R.F. source 41 is shown schematically interconnected between stem 39 and outer shell 35.
  • Soldering iron tip 33 makes particularly good use of the advantages of the composite heating element structure of the present invention.
  • the path of current flow through the structure of tip 33 is along stem 39 to its point of juncture with inner shell 37 and axially along the conical inside surface of tip 33 in an expanding current flow path to return to R.F. source 41.
  • a current flow path would inevitably produce excessive absorption of electric power at the apex portion of soldering iron tip 33, since the cross-section of the current flow path is smallest at this point and the resistance would in the usual case be higher therefore.
  • the result would be that unless large amounts of copper were used in the formation of outer shell 35, the apex region of tip 33 would be overheated while portions near the broad base of the cone received inadequate heat.

Landscapes

  • General Induction Heating (AREA)
  • Control Of Resistance Heating (AREA)
  • Cookers (AREA)

Claims (12)

1. Système de chauffage à autorégulation thermique utilisant les propriétés du point de Curie d'un matériau ferromagnétique de façon telle qu'au dessus d'une zone de températures s'élevant vers le point de Curie du matériau ferromagnétique, l'appareil de chauffage montre un coefficient de température négatif de résistance, le système de chauffage comprenant:
un premier conducteur électrique en matériau ferromagnétique,
un second conducteur en matériau non magnétique et dont la résistivité est plus faible que celle du premier conducteur,
et des bornes pour brancher ce système de chauffage à une source de courant à haute fréquence pour provoquer un courant alternatif d'amplitude suffisante pour faire monter la température du matériau ferromagnétique au moins jusqu'à la zone de température dans laquelle la perméabilité du matériau ferromagnétique décroit brutalement du fait que la température s'élève vers le point de Curie, caractérisé en ce qu'un conducteur est formé d'une couche entourant l'autre, et les deux conducteurs sont en contact thermique et électrique, le courant les traversant en parallèle, et du courant étant concentré par effet de peau dans le conducteur ferromagnétique, la proportion du courant s'écoulant à travers le conducteur ferromagnétique étant plus grande à des températures bien en dessous du point de Curie, que celle qui existe lorsque la température atteint la zone dans laquelle la perméabilité du matériau ferromagnétique décroît brutalement.
2. Système de chauffage selon la revendication 1, présentant la forme d'un cylindre.
3. Système de chauffage selon la revendication 2, ce cylindre possédant une section transversale circulaire.
4. Système de chauffage selon la revendication 1 ou 2, ce cylindre étant creux, et la couche de matériau ferromagnétique s'étendant de façon pratiquement continue sur l'une des surfaces de liaison de ce cylindre creux.
5. Système de chauffage selon la revendication 4, cette surface de liaison étant la surface extérieure de ce cylindre creux.
6. Système de chauffage selon la revendication 1, ayant la forme générale celle d'un cône.
7. Système de chauffage selon la revendication 6, ce cône étant creux et cette couche de matériau ferromagnétique s'étendant de façon pratiquement continue sur l'une des surfaces de liaison de ce cône creux.
8. Système de chauffage selon la revendication 7, cette surface de liaison étant la surface intérieure de ce cône.
9. Système de chauffage selon l'une quelconque des revendications précédentes, cette source de courant à haute fréquence étant couplée électriquement à l'élément chauffant par liaison ohmique.
10. Système de chauffage selon l'une quelconque des revendications précédentes, la source à haute fréquence fonctionnant dans la gamme des 8 à 20 MHz.
11. Système de chauffage selon l'une quelconque des revendications 1 à 5, la source de courant à haute fréquence étant reliée au courant de propagation axialement le long de ce cylindre.
12. Procédé de régulation de la température d'un appareil de chauffage par utilisation des propriétés du point de Curie d'un matériau ferromagnétique, comportant les étapes suivantes:
passage d'un courant alternatif d'amplitude constante à travers deux couches concentriques conductrices d'un matériau en parallèle, les couches se trouvant en contact thermique et électrique entre elles, l'une des couches étant ferromagnétique,
détermination de l'amplitude du courant à travers l'appareil de chauffage de telle sorte que sa température entraîne la perméabilité de la couche ferromagnétique dans une chute rapide vers une valeur de un mais sans attein- dre un.
EP81901612A 1981-03-02 1981-03-02 Element chauffant electriquement resistif possedant une commande de la temperature Expired - Lifetime EP0073190B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT81901612T ATE53737T1 (de) 1981-03-02 1981-03-02 Elektrisches widerstandheizelement mit temperaturregelung.

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US1981/000278 WO1982003148A1 (fr) 1981-03-02 1981-03-02 Element chauffant electriquement resistif possedant une commande de la temperature

Publications (3)

Publication Number Publication Date
EP0073190A1 EP0073190A1 (fr) 1983-03-09
EP0073190A4 EP0073190A4 (fr) 1983-06-15
EP0073190B1 true EP0073190B1 (fr) 1990-06-13

Family

ID=22161126

Family Applications (1)

Application Number Title Priority Date Filing Date
EP81901612A Expired - Lifetime EP0073190B1 (fr) 1981-03-02 1981-03-02 Element chauffant electriquement resistif possedant une commande de la temperature

Country Status (4)

Country Link
EP (1) EP0073190B1 (fr)
AT (1) ATE53737T1 (fr)
DE (1) DE3177193D1 (fr)
WO (1) WO1982003148A1 (fr)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4701587A (en) * 1979-08-31 1987-10-20 Metcal, Inc. Shielded heating element having intrinsic temperature control
CA1214815A (fr) * 1982-09-30 1986-12-02 John F. Krumme Dispositif de chauffage auto-stabilisateur a blindage electrique
US4752673A (en) * 1982-12-01 1988-06-21 Metcal, Inc. Autoregulating heater
DE3579605D1 (de) * 1984-03-06 1990-10-18 Metcal Inc Waermebehandlungsverfahren mittels selbstregulierender heizvorrichtung.
JP7112426B2 (ja) * 2017-06-28 2022-08-03 フィリップ・モーリス・プロダクツ・ソシエテ・アノニム エアロゾル形成基体を抵抗加熱するための電気加熱組立品、エアロゾル発生装置および方法

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1975436A (en) * 1929-11-08 1934-10-02 Ugine Infra Method of heating by induction and furnace therefor
US2181274A (en) * 1938-05-11 1939-11-28 Utilities Coordinated Res Inc Induction heater construction
US2513778A (en) * 1946-11-09 1950-07-04 Chrysler Corp Heat-treating apparatus
US3218384A (en) * 1962-03-29 1965-11-16 Int Nickel Co Temperature-responsive transmission line conductor for de-icing
US3660585A (en) * 1970-06-24 1972-05-02 Robert D Waldron Frozen shell metal melting means
US4017344A (en) * 1973-03-05 1977-04-12 Harold Lorber Magnetically enhanced coaxial cable with improved time delay characteristics
FR2233685B1 (fr) * 1973-06-12 1977-05-06 Josse Bernard
JPS5247583B2 (fr) * 1974-01-09 1977-12-03
US4091813A (en) * 1975-03-14 1978-05-30 Robert F. Shaw Surgical instrument having self-regulated electrical proximity heating of its cutting edge and method of using the same

Also Published As

Publication number Publication date
ATE53737T1 (de) 1990-06-15
DE3177193D1 (de) 1990-07-19
WO1982003148A1 (fr) 1982-09-16
EP0073190A4 (fr) 1983-06-15
EP0073190A1 (fr) 1983-03-09

Similar Documents

Publication Publication Date Title
US4256945A (en) Alternating current electrically resistive heating element having intrinsic temperature control
EP0075010B1 (fr) Element chauffant blinde pourvu d'une commande de temperature intrinseque
EP0110692B1 (fr) Elément de chauffage électrique à autorégulation
EP0107927B1 (fr) Elément de chauffage blindé électriquement à régulation intrinsèque
US4695713A (en) Autoregulating, electrically shielded heater
US5167545A (en) Connector containing fusible material and having intrinsic temperature control
CA1303104C (fr) Radiateur autoregulateur tres puissant
JP2530947B2 (ja) ワイヤ、パイプ、線条その他の部材の結合方法
RU2531292C2 (ru) Нагревательный кабель с минеральной изоляцией, работающий по принципу скин-эффекта
AU646498B2 (en) Switch controlled, zone-type heating cable and method
EP0582011B1 (fr) Chauffeurs et fers à braser-autorégulés en température
EP2052582B1 (fr) Appareil et procédé pour le chauffage par induction d'un matériau dans un canal
US1975437A (en) Induction heated furnace
KR20180014053A (ko) 온도 감지 전원 핀들을 가지는 저항성 히터
EP0073190B1 (fr) Element chauffant electriquement resistif possedant une commande de la temperature
CA1147381A (fr) Element chauffant par resistance a courant alternatif a regulation integree de la chaleur
US9907121B2 (en) Parallel wire conductor for use with a heating blanket
EP0180301B1 (fr) Réchauffeur autorégulant à haute efficacité
JPH05290960A (ja) 電気加熱装置
WO1992004164A1 (fr) Dispositif servant a couper une matiere
KR200208038Y1 (ko) 고주파 자기 유도 가열 다리미
KR20020005089A (ko) 유도 가열 고데기

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): AT CH DE FR GB LI LU NL SE

17P Request for examination filed

Effective date: 19830210

18D Application deemed to be withdrawn

Effective date: 19860911

18RA Request filed for re-establishment of rights before grant

Effective date: 19870525

18RR Decision to grant the request for re-establishment of rights before grant

Free format text: 880518 ANGENOMMEN

REG Reference to a national code

Ref country code: DE

Ref legal event code: 8570

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: METCAL INC.

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): AT CH DE FR GB LI LU NL SE

REF Corresponds to:

Ref document number: 53737

Country of ref document: AT

Date of ref document: 19900615

Kind code of ref document: T

REF Corresponds to:

Ref document number: 3177193

Country of ref document: DE

Date of ref document: 19900719

ET Fr: translation filed
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
EPTA Lu: last paid annual fee
EAL Se: european patent in force in sweden

Ref document number: 81901612.2

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

Ref country code: DE

Payment date: 20000306

Year of fee payment: 20

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

Ref country code: SE

Payment date: 20000307

Year of fee payment: 20

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

Ref country code: GB

Payment date: 20000308

Year of fee payment: 20

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

Ref country code: LU

Payment date: 20000309

Year of fee payment: 20

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

Ref country code: FR

Payment date: 20000310

Year of fee payment: 20

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

Ref country code: CH

Payment date: 20000313

Year of fee payment: 20

Ref country code: AT

Payment date: 20000313

Year of fee payment: 20

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

Ref country code: NL

Payment date: 20000330

Year of fee payment: 20

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

Ref country code: LI

Free format text: LAPSE BECAUSE OF EXPIRATION OF PROTECTION

Effective date: 20010301

Ref country code: GB

Free format text: LAPSE BECAUSE OF EXPIRATION OF PROTECTION

Effective date: 20010301

Ref country code: CH

Free format text: LAPSE BECAUSE OF EXPIRATION OF PROTECTION

Effective date: 20010301

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

Ref country code: NL

Free format text: LAPSE BECAUSE OF EXPIRATION OF PROTECTION

Effective date: 20010302

Ref country code: LU

Free format text: LAPSE BECAUSE OF EXPIRATION OF PROTECTION

Effective date: 20010302

Ref country code: AT

Free format text: LAPSE BECAUSE OF EXPIRATION OF PROTECTION

Effective date: 20010302

REG Reference to a national code

Ref country code: GB

Ref legal event code: PE20

Effective date: 20010301

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

Ref country code: SE

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

Effective date: 20010330

REG Reference to a national code

Ref country code: CH

Ref legal event code: PL

NLV7 Nl: ceased due to reaching the maximum lifetime of a patent

Effective date: 20010302

EUG Se: european patent has lapsed

Ref document number: 81901612.2