EP0359546B1 - Ultraschallanordnung mit verbesserter Kopplungsflüssigkeit - Google Patents

Ultraschallanordnung mit verbesserter Kopplungsflüssigkeit Download PDF

Info

Publication number
EP0359546B1
EP0359546B1 EP19890309295 EP89309295A EP0359546B1 EP 0359546 B1 EP0359546 B1 EP 0359546B1 EP 19890309295 EP19890309295 EP 19890309295 EP 89309295 A EP89309295 A EP 89309295A EP 0359546 B1 EP0359546 B1 EP 0359546B1
Authority
EP
European Patent Office
Prior art keywords
transducer
probe
ultrasound
window
coupling fluid
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
EP19890309295
Other languages
English (en)
French (fr)
Other versions
EP0359546A2 (de
EP0359546A3 (en
Inventor
Alan Paul Greenstein
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.)
HP Inc
Original Assignee
Hewlett Packard Co
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 Hewlett Packard Co filed Critical Hewlett Packard Co
Publication of EP0359546A2 publication Critical patent/EP0359546A2/de
Publication of EP0359546A3 publication Critical patent/EP0359546A3/en
Application granted granted Critical
Publication of EP0359546B1 publication Critical patent/EP0359546B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/18—Methods or devices for transmitting, conducting or directing sound
    • G10K11/26—Sound-focusing or directing, e.g. scanning
    • G10K11/35—Sound-focusing or directing, e.g. scanning using mechanical steering of transducers or their beams
    • G10K11/352—Sound-focusing or directing, e.g. scanning using mechanical steering of transducers or their beams by moving the transducer
    • G10K11/355—Arcuate movement
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/02—Mechanical acoustic impedances; Impedance matching, e.g. by horns; Acoustic resonators

Definitions

  • the present invention relates to ultrasound and, more particularly, to a system and method providing for improved coupling ultrasound between a transducer and a window of an ultrasound probe.
  • Ultrasonic imaging is widely used to analyze the internal structure of organisms. For example, ultrasound is often employed to characterize the status of a fetus in a pregnant woman. Ultrasonic imaging is based on the detection of reflections of ultrasonic waves at boundaries characterized by unequal impedances. Such boundaries can represent bones, organ boundaries, changes in tissue type, etc.
  • ultrasonic imaging is performed using an ultrasonic probe electrically coupled to an electronics module.
  • the probe generally comprises a body serving as a handle, a cap or window which can pressed against the skin of a subject being imaged, and a electro-acoustic transducer enclosed by the body and window.
  • the electronics module generates electrical pulses to be converted to ultrasonic pulses that are propagated through the window and into the subject.
  • a single ultrasonic pulse can result in multiple reflections due to multiple impedance boundaries along its path of propagation. As these reflections are detected by the probe, they are converted by the transducer to an electrical signal which represents depth by time and impedance mismatches by amplitude. The electronics module analyzes this signal to recover the imaging information which can then be displayed and/or recorded as desired.
  • the quality of the image obtained is largely dependent on the sensitivity with which the probe can detect reflections.
  • a substantial portion of the energy of an ultrasonic pulse is absorbed by the probe or the body. The remaining energy is distributed among multiple reflections. Only a small fraction of each reflection is directed toward the probe, and much of that small fraction is absorbed before reaching the transducer. The transducer must be able to detect the occurrences and amplitude of these reflections, despite the small amounts of energy in each reflection.
  • Sensitivity is a function of the aperture, or energy-gathering area, of the transducer.
  • a transducer with a large aperture can receive a greater portion of reflected acoustic energy.
  • a larger aperture implies a shallower depth of focus.
  • a transducer is shaped and/or operated so that there is, at any given time, a single depth at which the transducer's ability to resolve depth is at a maximum. In practice, maximal resolution is not necessary, but some threshold resolution below this maximum can be required by many imaging applications. When a transducer with a small aperture is used, the range of depths for which a given threshold is met or exceeded is larger than the corresponding range of depths available when a large aperture is used.
  • zooming When the range of depths of interest is greater than the depth of field of a probe, it is necessary to obtain imaging information using focal points at successive depths. Finer steps between focal points are required for a larger aperture.
  • zooming the process of changing the focal length of a probe during image gathering is referred to as "zooming".
  • Zooming permits high resolution imaging along a single trajectory.
  • the direction of ultrasound propagation must be panned, i.e., swept transversely or “steered”. It is this steering action that gives many ultrasound images their fan-shaped form.
  • steering and zooming are collectively referred to as “scanning”.
  • a small aperture probe with a spherical transducer can rely on a fixed focus and mechanical steering for imaging.
  • a single element transducer could be mechanically deformed to provide for zooming and, thus, larger apertures.
  • annular array transducers have been developed in which time delays between concentric elements provide the zooming function; annular array transducers generally employ mechanical steering.
  • phased-arrays are used in radar, it is possible to implement a rectangular array ultrasound transducer in which all scanning is performed electronically. Such rectangular arrays involve considerable processing complexity and are not widely used. Linear phased arrays are simpler to implement and also permit electronic zooming and steering; however, elevational resolution (transverse to depth and pan) is poor.
  • annular array stands out for allowing high resolution imaging in all directions while demanding less in the way of processing to generate an image from the received reflections. Zooming can be performed electronically at very high speeds for each mechanically controlled pan position.
  • One challenge in designing large aperture, mechanically scanned ultrasonic transducers such as an annular array transducers is to couple ultrasound transmissions between the probe and the subject optimally.
  • the moving transducer cannot be in intimate contact with the subject. Instead, intimate contact with the subject is made by the probe window.
  • the window material is selected to be safe, comfortable, rigid and transmissive of ultrasonic energy.
  • a more subtle criterion is the requirement that the acoustic refractive index at ultrasound frequencies be closely matched to the subject being imaged. In other words, the acoustic velocities of window and subject should be matched. The purpose of this matching is to minimize image distortion due to changes in beam direction at the subject-window boundary.
  • a fluid medium is typically interposed between a mechanically panned transducer and the associated probe window to permit steering motion while providing appropriate ultrasonic coupling between the transducer and the window and subject.
  • the requirements for coupling include matching of transmission velocity and impedance among the fluid, window and subject for the same reasons discussed above with respect to matching the window to the body.
  • the attenuation of the fluid must be considered to balance the requirement of efficient transmission of ultrasound and the need to damp reflections internal to the probe which could create image artifacts and otherwise degrade image quality.
  • One problem with known coupling fluids is that it is difficult to vary one parameter of interest, e.g., impedance, without affecting another, e.g., velocity. Often, it is not possible to "tweak" a fluid mixture to obtain the desired properties. Moreover, these properties must be maintained within acceptable tolerances over a range of operating tempertures, further excluding otherwise acceptable coupling fluids.
  • US-A-4 194 150 discloses an ultrasonic scanner using Glycerol as a coupling fluid.
  • the present invention is based on a probe design method which, rather than maximising its transmissivity, optimises the attenuation of the coupling fluid within a range selected to render the amplitudes of internal reflections insignificant by the time reflections of interest return to the probe transducer.
  • the coupling fluid between the transducer and a probe window includes a mixture of 1-Butanol and Glycerol, the ratio of 1-Butanol to Glycerol being between 23% and 37%. Attenuation can be adjusted downwardly by including a suitable amount of 2-Hydroxyethyl Ether with the mixture.
  • the invention is used to its best advantage in a mechanically scanned probe with a larger aperture transducer. However, it is also applicable to other ultrasonic probes employing a coupling fluid.
  • the distance between the transducer and the window and the length of the mean free path of ultrasound, i.e., acoustic energy having a frequency of about 20 kilohertz (kHz) or greater, through the medium are both relatively short. This results in relatively many reflections per unit time. Each reflection is accompanied by some attenuation and some dissipation or loss due to transmission; reflections off the transducer are particularly attenuative. By the time a reflection of interest arrives at the transducer, a sufficient number of internal reflections occur to reduce the energy of the internal reflections to an acceptable level.
  • the mean free path is longer and there are fewer reflections per unit time.
  • the coupling fluid in a large aperture probe serves a relatively more important role in attenuating internal reflections.
  • the present invention provides for a more attenuative coupling fluid than is typically employed in ultrasound probes.
  • the present invention provides for more precise control over the attenuation of the coupling fluid. Since the coupling fluid in a large aperture probe is a relatively important factor in attenuating internal reflections, it follows that performance of the incorporating ultrasound system is more sensitively affected by the extent of attenuation imposed by the coupling fluid. For this reason, it is important that the attenuation be precisely established at an optimum level.
  • the present invention addresses this problem in a probe which includes a coupling fluid the attenuation of which can be precisely adjusted without impairing velocity and impedance matching.
  • the ratio of 1-Butanol in Glycerol provides a relatively attenuative fluid. Lower attenuations are attainable by adding 2-Hydroxyethyl Ether. Small changes in velocity and impedance can be compensated by adjusting the ratio of 1-Butanol in Glycerol slightly.
  • the present invention provides for an economical and high performance ultrasound system.
  • the economy results from the greatly reduced design time required to find an appropriate coupling fluid to achieve different attenuations.
  • the fluid components are known as are the proportions required to attain specific levels of attenuation. This greatly relieves the amount of experimentation required to achieve optimal probe performance.
  • Probe performance is enhanced because larger aperture probes are made more practical and because attenuation can be more closely matched to probe characteristics and to applications.
  • FIGURE 1 is a sectional view of a probe in accordance with the present invention.
  • FIGURE 2 is a graph indicating the effect on attentuation and velocity of adding 2-Hydroxyethyl Ether to a mixture of 1-Butanol in Glycerol in accordance with the present invention.
  • FIGURE 3 is a flow chart depicting a method of coupling ultrasonic energy between a mechanically scanned ultrasound generator and an ultrasound window in accordance with the present invention.
  • An ultrasound system 101 includes an electronics module 103 and a probe 105, schematically shown in FIG. 1.
  • Electronics module 103 includes transmitter electronics 107 and receiver electronics 109 coupled via cable 111.
  • Cable 111 includes lines for supplying power and ground potentials to probe 105, for delivering pulses from transmitter electronics 107 to probe 105, for delivering received signals from probe 105 to receiver electronics 109.
  • a housing 113 for probe 105 includes a probe head 115, a probe back 117 and a probe handle 119.
  • Head 115 is attached to handle 119 via handle bracket 121.
  • a probe window 123 is rigidly attached to head 115.
  • Window 123, head 115 and back 117 collectively define a chamber 125 which is filled with a coupling fluid 127.
  • a transducer 131 is mounted in a spherical frame 133, which is pivotably mounted in head 115 with bearings 129.
  • a motor 135 is mounted in handle 119 by means of a motor mount 137. Motor 135 drives a pinion 139 via a shaft 141.
  • a shaft seal 143 prevents fluid 127 from escaping into handle 119.
  • Drive bands 145 transfer pinion motion to provide for steering of frame 133, and thus transducer 131.
  • Bands 145 are attached to frame 133 with bolts 147, one of two being shown.
  • An optical encoder 149 provides information on pan position to receiver electronics 109 required to construct an ultrasound image.
  • Ultrasound system 101 is typical of ultrasound systems using annular phased array transducers except for modifications to incorporate the relative large aperture transducer 131 for increased sensitivity and the selection of attenuative coupling fluid 127 to compensate noise problems introduced due to the increased aperture size.
  • the aperture of transducer 127 is about 3 centimeters (cm), compared to a more typical 1.5 cm aperture.
  • Coupling fluid 127 is substantially a two-component mixture consisting primarily of 1-Butanol (Butyl Alcohol) in Glycerol, the ratio of 1-Butanol to Glycerol being between 23% and 37%.
  • This two component mixture is characterised by a velocity of 1540 m/s, an impedance of 1.7 Mrayls and an attenuation of 4.1 dB/cm at 4.5 MHz. Temperature sensitivity is given by a velocity slope of -2.4 m/s/deg C and an attenuation slope of -0.1 dB/cm/deg.C. Both velocity and attenuation decrease with higher percentages of Butanol.
  • 2-Hydroxyethyl Ether is added to the mixture to reduce attenuation.
  • the effects of this addition for an illustrative composition are shown in FIG. 2.
  • 2-Hydroxyethlyl Ether there is insignificant change in attentuation and a small change in velocity to 1526 m/s.
  • FIG. 3 is a flow chart of a method in accordance with the present invention.
  • the first step 301 is mixing 1-Butanol into Glycerol to attain velocity and impedance matched levels.
  • the next step 302 is to add, as necessary, 2-Hydroxyethyl Ether to decrease attenuation to an appropriate level.
  • This fluid is to be enclosed, at step 303, in the head of the ultrasonic probe.
  • the window of the probe is to be pressed, at step 304, against a subject and the transducer of the probe mechanically scanned, at step 305, relative to the subject.
  • Ultrasound pulses are transmitted, at step 306, from the transducer through the fluid, through the window and into the subject. At least some of the ultrasound reflections from the subject are transmitted through the window, the fluid and converted, at step 307, by the transducer to electrical signals. These electrical signals are then analyzed, at step 308, to generate an image characterizing the subject.
  • the foregoing is a description of the preferred embodiments of the present invention.
  • different probe dimensions and geometries are accommodated.
  • a variety of transmission and receiver electronics are provided for, including both digital and analog based electronics.
  • Different transducer types and geometries are provided for.
  • the body supporting the transducer can have any of innumerable shapes and characteristics.
  • a variety of enclosure and window types and materials are provided for.
  • the drive system for steering the transducer can assume a variety of configurations.
  • the coupling fluid can include other components which modiX, dilute critical characteristics or which leave these characteristics unaffected but serve an ancillary function. Other modifications ad variations are provided for by the present invention, the scope of which is limited only by the following claims.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Ultra Sonic Daignosis Equipment (AREA)
  • Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
  • Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)

Claims (6)

  1. Ultraschallabtastkopf (101), der eine Kopplungsflüssigkeit (127) umfaßt, die zwischen einem Ultraschallwandler (131) und einem Abtastkopffenster (123) angeordnet ist, wobei besagte Kopplungsflüssigkeit Glycerin enthält, dadurch gekennzeichnet, daß besagte Kopplungsflüssigkeit außerdem 1-Butanol enthält, wobei das Verhältnis von 1-Butanol zu Glycerin zwischen 23% und 37% liegt.
  2. Vorrichtung nach Anspruch 1, dadurch gekennzeichnet, daß besagter Ultraschallwandler (131) elektrische Pulse in Ultraschallenergie und Ultraschallenergie in elektrische Signale umwandelt, wobei die Vorrichtung außerdem Übertragungselektronik (107), die mit besagtem Ultraschallwandler zur Lieferung besagter elektrischen Pulse an besagten Ultraschallwandler verbunden ist; und Empfangselektronik (109), die mit besagtem Ultraschallwandler zur Auswertung besagter elektrischen Signale verbunden ist, umfaßt.
  3. Vorrichtung nach einem der vorangegangenen Ansprüche, dadurch gekennzeichnet, daß sie außerdem einen Körper (113) umfaßt, der besagten Ultraschallwandler (131) trägt, so daß die Translationsstellung des Ultraschallwandlers durch Bewegen des Körpers kontrolliert werden kann, wobei besagte Umhüllung (115) fest mit besagtem Körper verbunden ist, und Antriebsmittel (135) besagten Ultraschallwandler relativ zu besagtem Körper bewegt, so daß die durch besagten Ultraschallwandler ausgestrahlte Ultraschallenergie relativ zu besagtem Körper abgetastet werden kann.
  4. Vorrichtung (101) nach irgendeinem der vorangegangenen Ansprüche, dadurch gekennzeichnet, daß besagte Flüssigkeit (127) auch 2-Hydroxyethyl Äther enthält.
  5. Verfahren zum Einkoppeln akustischer Energie in ein Ultraschallsystem, das in einem Abtastkopf (105) mit einem Ultraschallerzeuger (131) und einem Ultraschallfenster (123) enthalten ist, gekennzeichnet durch Füllen (303) des Raums zwischen besagtem Ultraschallerzeuger (131) und besagtem Ultraschallfenster (123) von besagtem Abtastkopf (105) mit einer Kopplungsflüssigkeit, die Glycerin enthält, und dadurch gekennzeichnet, daß besagte Kopplungsflüssigkeit außerdem 1-Butanol enthält, wobei das Verhältnis von 1-Butanol zu Glycerin in besagter Kopplungsflüssigkeit zwischen 23% und 37% liegt.
  6. Verfahren nach Anspruch 5, dadurch gekennzeichnet, daß es außerdem die folgenden Schritte umfaßt: Pressen (304) von besagten Ultraschallfenster (123) gegen einen Organismus; abtastendes Verfahren (305) des Ultraschallerzeugers (131) relativ zu besagtem Organismus; Übertragen (306) einer Serie von elektrischen Impulsen an besagten Ultraschallwandler (131), so daß eine Serie von Ultraschallpulsen erzeugt wird; Übertragen (306) besagter Ultraschallpulse von besagter Kopplungsflüssigkeit (127) durch besagtes Fenster (123) und in besagten Organismus, durch besagtes Fenster und durch besagte Flüssigkeit an besagten Ultraschallwandler, um elektrische Signale herzustellen; und Analysieren (308) besagter Signale, um besagten Organismus zu charakterisieren.
EP19890309295 1988-09-16 1989-09-13 Ultraschallanordnung mit verbesserter Kopplungsflüssigkeit Expired - Lifetime EP0359546B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US24612688A 1988-09-16 1988-09-16
US246126 1988-09-16

Publications (3)

Publication Number Publication Date
EP0359546A2 EP0359546A2 (de) 1990-03-21
EP0359546A3 EP0359546A3 (en) 1990-05-02
EP0359546B1 true EP0359546B1 (de) 1993-08-11

Family

ID=22929406

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19890309295 Expired - Lifetime EP0359546B1 (de) 1988-09-16 1989-09-13 Ultraschallanordnung mit verbesserter Kopplungsflüssigkeit

Country Status (3)

Country Link
EP (1) EP0359546B1 (de)
JP (1) JPH02116356A (de)
DE (1) DE68908307T2 (de)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE59209676D1 (de) * 1992-09-24 1999-05-20 Siemens Ag Intrakavitäre Ultraschallsonde
EP0749722A3 (de) * 1995-06-22 1997-04-16 Hewlett Packard Co Tragbarer Dreh-Ultraschall-Wandler
GB2457240B (en) 2008-02-05 2013-04-10 Fujitsu Ltd Ultrasound probe device and method of operation
WO2013139849A1 (en) 2012-03-20 2013-09-26 Alstom Technology Ltd Ultrasonic ndt sensor arrangement and method for inspecting surfaces of variable geometry of metal bodies

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4194510A (en) * 1978-06-15 1980-03-25 Second Foundation, Inc. Ultrasonic focusing system
JPS5885694A (ja) * 1981-11-18 1983-05-23 Hitachi Ltd ソ−ナシステム
GB2149916A (en) * 1983-11-16 1985-06-19 Britoil Plc Buoyant seismic streamer array
EP0455273B1 (de) * 1984-08-30 1996-10-30 Matsushita Electric Industrial Co., Ltd. Ultraschallwandler für medizinische Diagnostik

Also Published As

Publication number Publication date
DE68908307T2 (de) 1994-03-17
EP0359546A2 (de) 1990-03-21
EP0359546A3 (en) 1990-05-02
JPH02116356A (ja) 1990-05-01
DE68908307D1 (de) 1993-09-16

Similar Documents

Publication Publication Date Title
US6629929B1 (en) Method and apparatus for automatically setting the transmit aperture and apodization of an ultrasound transducer array
US5820564A (en) Method and apparatus for surface ultrasound imaging
US7135809B2 (en) Ultrasound transducer
US4455872A (en) Rotating ultrasonic scanner
US4339952A (en) Cylindrical transducer ultrasonic scanner
US4143554A (en) Ultrasonic scanner
US5678554A (en) Ultrasound transducer for multiple focusing and method for manufacture thereof
Karrer et al. A phased array acoustic imaging system for medical use
GB2027197A (en) Ultrasonic imaging apparatus
US4470305A (en) Annular array used as a horn transducer
US6409669B1 (en) Ultrasound transducer assembly incorporating acoustic mirror
US4257271A (en) Selectable delay system
US4442713A (en) Frequency varied ultrasonic imaging array
US5611343A (en) High resolution three-dimensional ultrasound imaging
Foster et al. The conical scanner: a two transducer ultrasound scatter imaging technique
CN104812311A (zh) 超声波探头及超声波诊断装置
EP0110593A2 (de) Verfahren und Gerät zur Ultraschallabtastung
US5911221A (en) Static scanhead switching along elevation for forming ultrasound beam line
US4410826A (en) Ultrasonic imaging apparatus using a coupling fluid mixture of propylene oxide, ethylene oxide derivative and glycerine
WO1990001171A1 (en) Ultrasonic reflex transmission imaging method and apparatus with artifact removal
Ylitalo On the signal-to-noise ratio of a synthetic aperture ultrasound imaging method
US5052393A (en) Ultrasound system with improved coupling fluid
EP0359546B1 (de) Ultraschallanordnung mit verbesserter Kopplungsflüssigkeit
GB2057131A (en) Ultrasonic sensing apparatus
CA1145449A (en) Conical transducer ultrasonic scanner

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

PUAL Search report despatched

Free format text: ORIGINAL CODE: 0009013

AK Designated contracting states

Kind code of ref document: A2

Designated state(s): DE FR GB IT NL

AK Designated contracting states

Kind code of ref document: A3

Designated state(s): DE FR GB IT NL

17P Request for examination filed

Effective date: 19900816

17Q First examination report despatched

Effective date: 19920325

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

ITF It: translation for a ep patent filed

Owner name: SOCIETA' ITALIANA BREVETTI S.P.A.

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): DE FR GB IT NL

REF Corresponds to:

Ref document number: 68908307

Country of ref document: DE

Date of ref document: 19930916

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

Ref country code: FR

Payment date: 19960814

Year of fee payment: 8

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

Ref country code: NL

Payment date: 19960820

Year of fee payment: 8

Ref country code: DE

Payment date: 19960820

Year of fee payment: 8

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

Ref country code: GB

Payment date: 19960828

Year of fee payment: 8

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: 19970913

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: 19970930

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 NON-PAYMENT OF DUE FEES

Effective date: 19980401

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

Effective date: 19970913

NLV4 Nl: lapsed or anulled due to non-payment of the annual fee

Effective date: 19980401

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: 19980603

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST

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 NON-PAYMENT OF DUE FEES

Effective date: 20050913