DK157819B - PROCEDURE FOR REGULATING THE SOUNDFIELD IN A LOCATION - Google Patents
PROCEDURE FOR REGULATING THE SOUNDFIELD IN A LOCATION Download PDFInfo
- Publication number
- DK157819B DK157819B DK112186A DK112186A DK157819B DK 157819 B DK157819 B DK 157819B DK 112186 A DK112186 A DK 112186A DK 112186 A DK112186 A DK 112186A DK 157819 B DK157819 B DK 157819B
- Authority
- DK
- Denmark
- Prior art keywords
- room
- sound
- absorption
- absorbent
- sound field
- Prior art date
Links
- 238000000034 method Methods 0.000 title claims description 4
- 230000001105 regulatory effect Effects 0.000 title description 2
- ZYXYTGQFPZEUFX-UHFFFAOYSA-N benzpyrimoxan Chemical compound O1C(OCCC1)C=1C(=NC=NC=1)OCC1=CC=C(C=C1)C(F)(F)F ZYXYTGQFPZEUFX-UHFFFAOYSA-N 0.000 claims 1
- 238000010521 absorption reaction Methods 0.000 description 15
- 230000002745 absorbent Effects 0.000 description 12
- 239000002250 absorbent Substances 0.000 description 12
- 239000000463 material Substances 0.000 description 9
- 230000010355 oscillation Effects 0.000 description 3
- 230000001419 dependent effect Effects 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 239000006096 absorbing agent Substances 0.000 description 1
- 230000003213 activating effect Effects 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000013016 damping Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 239000011491 glass wool Substances 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
- E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
- E04B1/99—Room acoustics, i.e. forms of, or arrangements in, rooms for influencing or directing sound
-
- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
- E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
- E04B1/62—Insulation or other protection; Elements or use of specified material therefor
- E04B1/74—Heat, sound or noise insulation, absorption, or reflection; Other building methods affording favourable thermal or acoustical conditions, e.g. accumulating of heat within walls
- E04B1/82—Heat, sound or noise insulation, absorption, or reflection; Other building methods affording favourable thermal or acoustical conditions, e.g. accumulating of heat within walls specifically with respect to sound only
- E04B2001/8263—Mounting of acoustical elements on supporting structure, e.g. framework or wall surface
- E04B2001/829—Flat elements mounted at an angle, e.g. right angle, to the supporting surface
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Architecture (AREA)
- Acoustics & Sound (AREA)
- Electromagnetism (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Building Environments (AREA)
- Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
Description
DK 157819BDK 157819B
iin
Opfindelsen angår en fremgangsmåde til regulering af lydfeltet i et lokale, herunder efterklangstiden i lokalet, ved hjælp af lydabsorberende elementer anbragt i hjørnerne af lokalet.The invention relates to a method for regulating the sound field in a room, including the reverberation time in the room, by means of sound absorbing elements arranged in the corners of the room.
5 Det er kendt at anbringe lydabsorberende elementer i hjørnerne af et lokale - jvf. f.eks. europæisk patentansøgning nr. 37.610. Dette giver imidlertid en frekvensafhængig dæmpningskarakteristik med et kraftigt dyk.5 It is known to place sound-absorbing elements in the corners of a room - cf. European Patent Application No. 37,610. However, this provides a frequency-dependent attenuation characteristic with a strong dive.
10 Ifølge opfindelsen er det anvist, hvorledes man undgår dette dyk i dæmpningskarakteristikken, og dette formål er ifølge opfindelsen opnået ved, at man ved målinger fastlægger de områder i hjørnet, hvor lydfeltet er særlig kraftigt, hvorefter man tilpasser de lydabsorberende elementer således, at de 15 strækker sig gennem disse områder. Forsøg har vist, at man derved undgår det kraftige dyk i dæmpningskarakteristikken. Endvidere opnås en bedre udnyttelse af dæmpningsmaterialet, idet det nu virker der, hvor lydfeltet er kraftigst.According to the invention, it is disclosed how to avoid this dive in the attenuation characteristic, and this object is achieved according to the invention by defining in the corner the areas in which the sound field is particularly strong, after which the sound absorbing elements are adapted so that the 15 extends through these areas. Experiments have shown that this avoids the strong dive in the damping characteristic. Furthermore, better utilization of the cushioning material is obtained, since it now works where the sound field is most powerful.
20 Opfindelsen skal nærmere forklares i det følgende under henvisning til tegningen, hvor fig. 1 viser en kendt diagonal absorbent til anbringelse i et hjørne, 25 fig. 2a og 2b afbildninger af Ekin/Epot af et diffust lydfelt i et hjørne, fig. 3 isoabsorbtionskurver (Ekin/Epot konstant) med diagonal-30 absorbenter indlagt, med forskellige forhold mellem størrelse og bølgelængde, fig. 4 absorptionen som funktion af frekvensen, 35 fig. 5a-5e absorptionen som funktion af frekvensen ved forskellige udformninger af absorbenten, idet fig. 5d viser absorptionselementet anbragt i overensstemmelse med fremgangsmåden ifølge opfindelsen ogThe invention will be explained in more detail below with reference to the drawing, in which 1 shows a known diagonal absorbent for placement in a corner; FIG. Figures 2a and 2b show Ekin / Epot of a diffuse sound field in a corner; 3 isoabsorption curves (Ekin / Epot constant) with diagonal absorbents inlaid, with different size-wavelength ratios; 4 shows the absorption as a function of frequency; FIG. 5a-5e the absorption as a function of the frequency of different designs of the absorbent; 5d shows the absorption element disposed in accordance with the method of the invention and
2 DK 157819 B2 DK 157819 B
fig. 6 strømningsmodstanden som funktion af densiteten.FIG. 6 the flow resistance as a function of density.
Ved frekvenser over ca 100 - 300 Hz sker lydabsorptionen i den i fig. 1 viste diagonalabsorbent under luftpartiklernes bevæg-5 else i et porøst ubevægeligt materiale. Absorbenten anbringes i et hjørne, hvor der optræder store luftpartikelhastigheder -se fig. 2.At frequencies above about 100 - 300 Hz, the sound absorption in the embodiment of FIG. 1 shows the diagonal absorbent during the movement of the air particles in a porous motionless material. The absorbent is placed in a corner where large air particle velocities occur - see FIG. 2nd
Den frekvens fj, ved hvilken absorptionen er maksimal, kan 10 bestemmes ud fra teoretiske analyser af lydfeltet i et hjørne, idet f 1 = 140 = 28J0 Hz d i*sin28 15 hvor d er dybden af absorbenten i meter, medens i og Θ er angivet i fig. 1.The frequency fj at which the absorption is maximal can be determined from theoretical analyzes of the sound field in a corner, where f 1 = 140 = 28J0 Hz di * sin28 15 where d is the depth of the absorbent in meters, while i and Θ in FIG. First
Ved lavere frekvenser (50 - 200 Hz) og for diagonalabsorbenter 20 med i mindre end 2 m sker lydabsorptionen overvejende ved, at pladematerialet sættes i resonanssvingninger, idet energien absorberes som følge af tab i materialet og tab langs randene, hvor materialet er fastgjort. Ved aktivering af disse resonanssvingninger er det områderne i lydfeltet med store tryk-25 variationer, der har betydning.At lower frequencies (50 - 200 Hz) and for diagonal absorbers 20 with less than 2 m, the sound absorption is predominantly by resonating the sheet material, absorbing the energy as a result of loss in the material and loss along the edges where the material is attached. When activating these resonance oscillations, the areas of the sound field with large pressure variations are important.
For en plan diagonalabsorbent med ringe bøjningsstivhed i forhold til stivheden af den indespærrede luft bliver resonansfrekvensen : 30 f0 = 120 Hz ^ m,l*sin(28) hvor m er pladematerialets masse pr. arealenhed i kg/m2, og i 35 er længden i meter. Førstnævnte virkemåde ved højere frekvenser indebærer visse krav til størrelse, form og strømningsmodstand. Den anden virkemåde ved lavere frekvenser indebærer visse krav til størrelse og masse pr. arealenhed.For a planar diagonal absorbent having a low bending stiffness relative to the stiffness of the trapped air, the resonant frequency becomes: 30 f0 = 120 Hz ^ m, l * sin (28) where m is the mass of the sheet material per minute. area unit in kg / m2, and in 35 is the length in meters. The former at higher frequencies involves certain requirements for size, shape and flow resistance. The second mode of operation at lower frequencies involves certain size and mass requirements per day. unit area.
DK 157819 BDK 157819 B
33
Der tilstræbes størst mulig lydabsorption i frekvensområdet 100 - 4000 Hz, og absorptionen bør forløbe så jævnt som muligt i dette frekvensområde.The highest possible sound absorption is sought in the frequency range 100 - 4000 Hz and the absorption should proceed as smoothly as possible in this frequency range.
5 Eksperimentelle undersøgelser har givet lovende resultater for £ = 0,90 m og Θ = 30®, gældende for plane diagonalabsorbenter.5 Experimental studies have yielded promising results for £ = 0.90 m and Θ = 30®, applicable to planar diagonal absorbents.
Ud fra teoretiske analyser kan forventes endnu bedre resultater for specielle, ikke plane udformninger - se fig. 5d. Omvendt kan der forventes ujævne frekvensforløb ved særlig uhen-10 sigtsmæssige udformninger. Hvis dimensionerne bliver for små, opstår der problemer ved lave frekvenser. Desuden er det opnåelige absorptionsareal direkte afhængigt af absorbentens overf ladeareal.From theoretical analyzes, even better results can be expected for special, non-planar designs - see fig. 5d. Conversely, uneven frequency loss can be expected in particularly inappropriate designs. If the dimensions get too small, problems will occur at low frequencies. In addition, the achievable absorption area is directly dependent on the absorbent surface area.
15 Eftersom resonansfrekvensen fQ bør ligge ved omkring 100 Hz, og i antages at ligge i området 0,90 - 1,80 m, fås følgende krav til masse pr. arealenhed: m = 1 - 2 kg/m2, 20 idet massen pr. arealenhed skal være størst for små værdier af £. Forsøg har vist, at strømningsmodstanden £ bør være noget større end for traditionelle nedhængte loftsplader, formentlig omkring: r = 2000 - 2500 Ns/m2. Disse størrelser afhænger af 25 pladetykkelsen h samt af egentlige materialeparametre efter formlen: m = p*h, hvor p er massefylden, og r = s*h, hvor Ξ er den specifikke strømningsmodstand.Since the resonant frequency fQ should be at about 100 Hz and is assumed to be in the range of 0.90 - 1.80 m, the following mass requirements are obtained. area unit: m = 1 - 2 kg / m2; area unit must be larger for small values of £. Tests have shown that the flow resistance £ should be somewhat greater than that of traditional suspended ceiling panels, probably around: r = 2000 - 2500 Ns / m2. These sizes depend on the plate thickness h as well as the actual material parameters of the formula: m = p * h, where p is the density, and r = s * h, where Ξ is the specific flow resistance.
3030
Man får således _S_ * 1.250 s"1There is thus obtained _S_ * 1,250 s "1
PP
35 hvilket kan indtegnes som en linie i et Ξ-ρ-diagram - se fig.35 which can be plotted as a line in a Ξ-ρ diagram - see FIG.
6. Dette kunne indikere, at den optimale fiberdiameter er noget mindre end for almindelig glasuld. Alternativt kan der an6. This could indicate that the optimum fiber diameter is somewhat smaller than that of ordinary glass wool. Alternatively, there may be
DK 157819 BDK 157819 B
4 vendes en overfladebelægning, som forøger strømningsmodstanden passende.4, a surface coating is applied which appropriately increases the flow resistance.
Endelig er der grænser for, hvor stor den specifikke strøm-5 ningsmodstand bør være for at undgå at høje frekvenser reflekteres fra en for hårdt sammenpresset overflade. Materialeparametrene vil kunne vælges inden for følgende interval: h p Ξ 10 20 mm 100 kg/m3 125·103 Ns/m* 40 mm 50 kg/m3 63·103 Ns/m4.Finally, there are limits to how much the specific flow resistance should be to avoid reflecting high frequencies from an overly compacted surface. The material parameters can be selected within the following range: h p Ξ 10 20 mm 100 kg / m3 125 · 103 Ns / m * 40 mm 50 kg / m3 63 · 103 Ns / m4.
15 Fig. 5a - e viser karakteristikkerne for forskellige udformninger af absorptionselementet. I fig. 5a ses et ovalt absorptionselement, der giver en meget uensartet frekvenskarakteristik, idet frekvenskarakteristikken udviser et kraftigt dyk ved d/λ = 0,7 svarende til, at absorptionselementet i dette 20 tilfælde er placeret dér, hvor svingningerne er svagest. Også den i fig. 5b viste diagonalabsorbent giver en meget dårlig karakteristik, idet det i alle tilfælde kun er en del af ab-sorbenten, der er anbragt dér, hvor svingningerne er kraftigst.FIG. Figures 5a - e show the characteristics of different designs of the absorption element. In FIG. Fig. 5a shows an oval absorption element which gives a very uneven frequency characteristic, the frequency characteristic exhibiting a strong dive at d / λ = 0.7 corresponding to the absorption element in this case being located where the oscillations are weakest. Also shown in FIG. 5b gives a very poor characteristic, since in all cases only a part of the absorbent is located where the oscillations are strongest.
Det hjælper lidt, hvis di agonalabsorbenten anbringes usymme-25 trisk med en vinkel, der er forskellig fra 45°. Fig. 3 viser, hvorledes en sådan absorbent indvirker på lydfeltet ved forskellige frekvenser. Det ses, at karakteristikken nødvendigvis må udvise et dyk (i det viste tilfælde ved ca. 500 Hz). Fig.It is of little help if the diagonal absorbent is placed unsymmetrically at an angle different from 45 °. FIG. 3 shows how such an absorbent affects the sound field at different frequencies. It is seen that the characteristic must necessarily exhibit a dive (in the case shown at about 500 Hz). FIG.
5d viser en mere ideel udformning af absorptionselementet, 30 idet absorptionselementet placeres i områder, hvor lydfeltet er særlig kraftigt. Fig. 5e viser absorptionselementet i en alternativ asymmetrisk udførelse (asymmetrisk L-formet).5d shows a more ideal configuration of the absorption element, with the absorption element being placed in areas where the sound field is particularly strong. FIG. 5e shows the absorption element in an alternative asymmetric embodiment (asymmetrical L-shaped).
Fig. 6 viser strømningsmodstandene som funktion af densiteten 35 for forskellige materialetyper.FIG. 6 shows the flow resistances as a function of density 35 for different types of materials.
De lydabsorberende elementer kan eventuelt ændres i afhængighed af é-n eller flere parameterværdier i lokalet, eventueltThe sound absorbing elements may be changed depending on one or more parameter values in the room, optionally
Claims (1)
Priority Applications (17)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DK112186A DK157819C (en) | 1986-03-11 | 1986-03-11 | PROCEDURE FOR REGULATING THE SOUNDFIELD IN A LOCATION |
| DE19873705438 DE3705438A1 (en) | 1986-03-11 | 1987-02-20 | DEVICE FOR REGULATING THE LIGHT IMAGE INCL. THE REVERON TIME IN A ROOM |
| NO870806A NO870806L (en) | 1986-03-11 | 1987-02-26 | DEVICE FOR REGULATING THE SOUND IMAGE, INCLUDING THE LANGUAGE IN A LOCATION. |
| IT19558/87A IT1202617B (en) | 1986-03-11 | 1987-03-03 | DEVICE TO ADJUST THE FEATURES OF A SOUND, INCLUDING THE REVERBERATION TIME IN A ROOM |
| NL8700513A NL8700513A (en) | 1986-03-11 | 1987-03-03 | DEVICE FOR ADJUSTING THE SOUND CARTRIDGE INCLUDING THE RENAL TIME IN A ROOM. |
| GR870367A GR870367B (en) | 1986-03-11 | 1987-03-05 | A device regulating the sound pattern including the time of rever beration in a room |
| CH845/87A CH674043A5 (en) | 1986-03-11 | 1987-03-06 | |
| ES8700626A ES2002991A6 (en) | 1986-03-11 | 1987-03-06 | Controlling sound reverberation characteristics of a room |
| FR8703086A FR2595856A1 (en) | 1986-03-11 | 1987-03-06 | DEVICE FOR ADJUSTING THE ACOUSTICITY OF A PIECE |
| FI871014A FI83117C (en) | 1986-03-11 | 1987-03-09 | FOERFARANDE FOER REGLERING AV LJUDFAELTET, SAOSOM EFTERKLANGSTIDEN, I ETT RUM. |
| GB8705590A GB2188186B (en) | 1986-03-11 | 1987-03-10 | Device and method for controlling sound reverberation in a room |
| CA000531600A CA1294893C (en) | 1986-03-11 | 1987-03-10 | Device adjusting the sound pattern including the time of reverberation in a room |
| SE8700983A SE8700983L (en) | 1986-03-11 | 1987-03-10 | DEVICE FOR REGULATING THE SOUND IMAGE, OTHER THAN THE REVOLUTION, IN A LOCAL |
| JP62053195A JPS63113322A (en) | 1986-03-11 | 1987-03-10 | Regulator for indoor acoustic pattern |
| IE60387A IE59607B1 (en) | 1986-03-11 | 1987-03-10 | Device and Method for Controlling Sound Reverberation in a Room |
| PT84453A PT84453B (en) | 1986-03-11 | 1987-03-11 | DEVICE FOR ADJUSTING ACOUSTICS IN A ROOM, INCLUDING THE REVERBANKING TIME |
| BE8700239A BE1000032A7 (en) | 1986-03-11 | 1987-03-11 | Adjusting device distribution sound including reverb time in a local. |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DK112186A DK157819C (en) | 1986-03-11 | 1986-03-11 | PROCEDURE FOR REGULATING THE SOUNDFIELD IN A LOCATION |
| DK112186 | 1986-03-11 |
Publications (4)
| Publication Number | Publication Date |
|---|---|
| DK112186D0 DK112186D0 (en) | 1986-03-11 |
| DK112186A DK112186A (en) | 1987-09-12 |
| DK157819B true DK157819B (en) | 1990-02-19 |
| DK157819C DK157819C (en) | 1990-09-10 |
Family
ID=8101249
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| DK112186A DK157819C (en) | 1986-03-11 | 1986-03-11 | PROCEDURE FOR REGULATING THE SOUNDFIELD IN A LOCATION |
Country Status (17)
| Country | Link |
|---|---|
| JP (1) | JPS63113322A (en) |
| BE (1) | BE1000032A7 (en) |
| CA (1) | CA1294893C (en) |
| CH (1) | CH674043A5 (en) |
| DE (1) | DE3705438A1 (en) |
| DK (1) | DK157819C (en) |
| ES (1) | ES2002991A6 (en) |
| FI (1) | FI83117C (en) |
| FR (1) | FR2595856A1 (en) |
| GB (1) | GB2188186B (en) |
| GR (1) | GR870367B (en) |
| IE (1) | IE59607B1 (en) |
| IT (1) | IT1202617B (en) |
| NL (1) | NL8700513A (en) |
| NO (1) | NO870806L (en) |
| PT (1) | PT84453B (en) |
| SE (1) | SE8700983L (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2281539A (en) * | 1993-09-01 | 1995-03-08 | Torrington Co | Adjustable vehicle steering column assembly |
| WO2003002955A1 (en) * | 2001-06-28 | 2003-01-09 | Kkdk A/S | Method and system for modification of an acoustic environment |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB375726A (en) * | 1931-01-28 | 1932-06-30 | Marconi Wireless Telegraph Co | Improvements in or relating to acoustic adjusting apparatus for use in sound studiosand the like |
| GB496384A (en) * | 1936-03-26 | 1938-11-25 | Waldemar Oelsner | Improved means for controlling the acoustic properties of rooms |
| SE427364B (en) * | 1980-04-09 | 1983-03-28 | A & K Byggnadsfysik Ab | DIAGONALLY MOUNTED SOUND ABSORBENT |
-
1986
- 1986-03-11 DK DK112186A patent/DK157819C/en not_active IP Right Cessation
-
1987
- 1987-02-20 DE DE19873705438 patent/DE3705438A1/en not_active Withdrawn
- 1987-02-26 NO NO870806A patent/NO870806L/en unknown
- 1987-03-03 NL NL8700513A patent/NL8700513A/en not_active Application Discontinuation
- 1987-03-03 IT IT19558/87A patent/IT1202617B/en active
- 1987-03-05 GR GR870367A patent/GR870367B/en unknown
- 1987-03-06 ES ES8700626A patent/ES2002991A6/en not_active Expired
- 1987-03-06 CH CH845/87A patent/CH674043A5/de not_active IP Right Cessation
- 1987-03-06 FR FR8703086A patent/FR2595856A1/en active Pending
- 1987-03-09 FI FI871014A patent/FI83117C/en not_active IP Right Cessation
- 1987-03-10 IE IE60387A patent/IE59607B1/en not_active IP Right Cessation
- 1987-03-10 JP JP62053195A patent/JPS63113322A/en active Pending
- 1987-03-10 GB GB8705590A patent/GB2188186B/en not_active Expired - Fee Related
- 1987-03-10 SE SE8700983A patent/SE8700983L/en not_active Application Discontinuation
- 1987-03-10 CA CA000531600A patent/CA1294893C/en not_active Expired
- 1987-03-11 BE BE8700239A patent/BE1000032A7/en not_active IP Right Cessation
- 1987-03-11 PT PT84453A patent/PT84453B/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| IE59607B1 (en) | 1994-03-09 |
| GB2188186A (en) | 1987-09-23 |
| DK112186D0 (en) | 1986-03-11 |
| ES2002991A6 (en) | 1988-10-01 |
| JPS63113322A (en) | 1988-05-18 |
| FI83117C (en) | 1991-05-27 |
| GB2188186B (en) | 1990-02-14 |
| NO870806D0 (en) | 1987-02-26 |
| NL8700513A (en) | 1987-10-01 |
| GR870367B (en) | 1987-07-10 |
| FR2595856A1 (en) | 1987-09-18 |
| FI83117B (en) | 1991-02-15 |
| DK157819C (en) | 1990-09-10 |
| CH674043A5 (en) | 1990-04-30 |
| FI871014A (en) | 1987-09-12 |
| IT8719558A0 (en) | 1987-03-03 |
| FI871014A0 (en) | 1987-03-09 |
| PT84453B (en) | 1989-10-04 |
| GB8705590D0 (en) | 1987-04-15 |
| DK112186A (en) | 1987-09-12 |
| SE8700983D0 (en) | 1987-03-10 |
| SE8700983L (en) | 1987-09-12 |
| BE1000032A7 (en) | 1987-11-24 |
| NO870806L (en) | 1987-09-14 |
| IT1202617B (en) | 1989-02-09 |
| PT84453A (en) | 1987-04-01 |
| DE3705438A1 (en) | 1987-09-17 |
| IE870603L (en) | 1987-09-11 |
| CA1294893C (en) | 1992-01-28 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PBP | Patent lapsed |