CA1129269A - Structural material for acoustic machines and instruments - Google Patents
Structural material for acoustic machines and instrumentsInfo
- Publication number
- CA1129269A CA1129269A CA331,208A CA331208A CA1129269A CA 1129269 A CA1129269 A CA 1129269A CA 331208 A CA331208 A CA 331208A CA 1129269 A CA1129269 A CA 1129269A
- Authority
- CA
- Canada
- Prior art keywords
- instruments
- pores
- structural material
- acoustic
- rubber
- 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
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/009—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone characterised by the material treated
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B26/00—Compositions of mortars, concrete or artificial stone, containing only organic binders, e.g. polymer or resin concrete
- C04B26/02—Macromolecular compounds
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
- C04B38/0051—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof characterised by the pore size, pore shape or kind of porosity
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
- C04B41/46—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with organic materials
- C04B41/48—Macromolecular compounds
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/80—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only ceramics
- C04B41/81—Coating or impregnation
- C04B41/82—Coating or impregnation with organic materials
- C04B41/83—Macromolecular compounds
-
- 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
- G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/162—Selection of materials
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B19/00—Driving, starting, stopping record carriers not specifically of filamentary or web form, or of supports therefor; Control thereof; Control of operating function ; Driving both disc and head
- G11B19/20—Driving; Starting; Stopping; Control thereof
- G11B19/2009—Turntables, hubs and motors for disk drives; Mounting of motors in the drive
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B33/00—Constructional parts, details or accessories not provided for in the other groups of this subclass
- G11B33/02—Cabinets; Cases; Stands; Disposition of apparatus therein or thereon
- G11B33/08—Insulation or absorption of undesired vibrations or sounds
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Multimedia (AREA)
- Acoustics & Sound (AREA)
- Physics & Mathematics (AREA)
- Details Of Audible-Bandwidth Transducers (AREA)
- Soundproofing, Sound Blocking, And Sound Damping (AREA)
- Porous Artificial Stone Or Porous Ceramic Products (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Powder Metallurgy (AREA)
- Compositions Of Oxide Ceramics (AREA)
- Ceramic Products (AREA)
- Application Of Or Painting With Fluid Materials (AREA)
- Holding Or Fastening Of Disk On Rotational Shaft (AREA)
Abstract
TITLE OF THE INVENTION:
Structural material for acoustic machines and instruments ABSTRACT OF THE DISCLOSURE:
A structural material for acoustic machines and instruments, which consists of a sintered ceramic body wherein porosity is more than 20%, the diameter of pores is less than 300 microns on an average and at least part of pores is impregnated with rubber and/or resin.
Structural material for acoustic machines and instruments ABSTRACT OF THE DISCLOSURE:
A structural material for acoustic machines and instruments, which consists of a sintered ceramic body wherein porosity is more than 20%, the diameter of pores is less than 300 microns on an average and at least part of pores is impregnated with rubber and/or resin.
Description
65~
This invention relates to an improvment in or relating to a structural material for acoustic machines and instruments As the materials for turntable, turntable sheet, stabilizer 9 speaker enclosure 9 floor system enclosure 9 head shell and tone arm of acoustic machines and instruments 9 particularly of record player there were hitherto employed mainly metals such as aluminium die casting and press worked steel plate and wood in view of easy workabilityg rigidity and appearance to some extent, and moderate cost9 in the hope that (1) said materials may have a great equi~alent mass and a high rigidity so as to hardly vibrate, and that (2) they may have a great damping ratio to vibration thereby attenuating vibration quickly 9 said two features (1) and (2) being of properties of making acoustic effects good~
Among said products 9 however9 the metallic ones have a very small damping ratio to vibration but 2Q a high resonance sharpness fh so that they have demerits in likelihood of resonance to specific frequency~
They are liable to receive the vib.ration of motor9 the outside vibration transmitted through player board and the vibration of speaker so as to deteriorate the signal-to-noise ratio9 thereby causing sometimes howlingO Wooden speaker enclosure is resonant even with specific resonance~ To prevent this unfavorable effect there has been provided means that the upper or lower face of a turntable is coated or adhered with a substance having a great damping ratio of vibration9 such as resin or rubber,or it is sticked together with - composite plastics. However, in the former case it is impossible to completely control the properties innate to the metallic body because the resin or rubber is a complement to the metallic bodyO To answer the purpose 9 therefore, the resin or rubber must be greater in mass than the metallic body whereby the rigidity of metal can no longer be effectively usedc In the latter case the main skeleton is of plastics so that it lacks in rigidity and the turntable causes damping action to swing the disc up and down, while causing a fear of troubling the tracing operation of stylus chip~
Further, being light in weight with regard to plastics9 its mass is small when the content of filler is less to lack in the inertia mass of said turntable thereby causing wow and flutter as in a turntable of metal plate~ ~urthermore, wooden articles have a great damping ratio but they come short of rigidityO
The object of the invention is to provide materials for acoustic machines and instruments of the kind described at the beginning of the specifica-tion9 said machines and instruments excluding the conventional demerits and having good performance~
The turntalbe according to the invention consists of a sintered ceramic body wherein porosity is more than 20% and the diameter of the pores is less than 300 microns on an average9 and at least part of the pores of said sintered body is impregnated with elastic materials such as rubber and/or resin . T~e great rigidity '~
and mass possessed by ceramic may serve for less sensitivity against vibration of the turntalbe and for quickly attenuating the vibration thanks to the pores of ceramicO In the ceramic fit for the material of the acoustic machines and instruments according to the invention, the greater in rigidity the betterO
However, the allowable lower limit o~ the rigidity will be a Knoop hardness of more than 500 to fall under a range in which the strain by vibration does ' 10 not badly affects the sound effectsO This means that materials harder than ceramic or glass can be usedO
Further9 preferably the ratio of the pores which attenuate the damping ratio of vibration as quickly as possible is more than 20% porosity9 and the porosity of less than 20% will have less effect because it can-not sufficiently form pores included between crystal particles of ceramic in order to promptly decrease the vibration added to,the ceramic body. Accordi.nglys the less in the size of pores the wider they disperse so that the pores can be included more between the crystals and particles of ceramic to increase the attenuating properties of inside vibrationp but ceramic having an average pore diameter of less than 300 microns can satisfy these requirements and it is effective for increasing the damping ratio of vibration to impregnate the interior of the pores of ceramac having said ~ores with elastic substances such as rubber and/or resin in place of air.
That is, the rubber or resin is acti~e for enclosing the vibration whiçh ~Jas subject to the crystals or particles of.cera~ic to be a rigid body, into the 1 1 2 ~ 2 crystals or perticles 9 thereby attenuating the vibra-tionO The i~pregnation ~.ay not necessarily be carried out over the entirc pores 9 and it may be restricted to the upper f ace and lower f ace of the material to be treated or non-uniformly dispersed in its entiretyO ~dvantageously~ the turntable which is impregnated with rubber or resin at its upper face will not require a turnt&ble sheet made of rubberO
The invention will now be described more in detail 9 by way o-. examples 9 with reference to a turn-tableO
- Ceramic material is added with kaolin of more than 10% and then wet mixed with a small amount of combustible material and water~ The mixture is moulded by pressing such as under hydraulic pressure9 air pressure, oil pressure or friction9 and after drying it is sintesed in a sintering furnaceO After cooling the sintered article, its surface is faced thereby grinding and processing it to a,desired extent of preciseness of dimension and shapeO The mixed combustible materials are effective for forming pores9 and there are used wax, fine powder of wood9 starch9 wheat powder and the likeO
Impregnation of the elastic substances may be carried out in a liquid state of said substances9 such as latex of natural or artificial rubber besides a carbon disulIide solutionlo~ rubber9 an alcohol solution of resin or the like 9 by either coating it onto the surface of turntable or dipping the turntakle in it thereafter dryingO
Mixing examples and the properties of the sintered pieces of ceramic produced with said mixing are now described hereunderO
(a) Alumina (250 ~) 87%
Kaolin 13%
Porosity 32%
Average pore diameter 150 Bulk specific gravity 2047 Hardness 2200 Knoop (b) Silicon carbide (125~) 85%
Kaolin 15%
Porosity 31%
Average pore diameter 45~
Bulk specific gravity 2004 Hardness 2400 Knoop As a mode of working of the invention, a test listening was carried out by acoustic specialists by using a disc turntable in which a turntable sheet made of baked ceramic impregnated withsilicon rubber was adhered onto a conventional turntable made of alumi-nium die casting, with an adhesive. As a result, it was proved that compared with conventional aluminium die casting disc turntable with rubber sheet 9 there was scarcely resonance caused by mechanical vibration9 sound effects of high damping effect were exerted9 and acoustic properties thanks to the rigidity and porosity of ceramic are very prominent, said properties being a technical idea of the inventionO
_
This invention relates to an improvment in or relating to a structural material for acoustic machines and instruments As the materials for turntable, turntable sheet, stabilizer 9 speaker enclosure 9 floor system enclosure 9 head shell and tone arm of acoustic machines and instruments 9 particularly of record player there were hitherto employed mainly metals such as aluminium die casting and press worked steel plate and wood in view of easy workabilityg rigidity and appearance to some extent, and moderate cost9 in the hope that (1) said materials may have a great equi~alent mass and a high rigidity so as to hardly vibrate, and that (2) they may have a great damping ratio to vibration thereby attenuating vibration quickly 9 said two features (1) and (2) being of properties of making acoustic effects good~
Among said products 9 however9 the metallic ones have a very small damping ratio to vibration but 2Q a high resonance sharpness fh so that they have demerits in likelihood of resonance to specific frequency~
They are liable to receive the vib.ration of motor9 the outside vibration transmitted through player board and the vibration of speaker so as to deteriorate the signal-to-noise ratio9 thereby causing sometimes howlingO Wooden speaker enclosure is resonant even with specific resonance~ To prevent this unfavorable effect there has been provided means that the upper or lower face of a turntable is coated or adhered with a substance having a great damping ratio of vibration9 such as resin or rubber,or it is sticked together with - composite plastics. However, in the former case it is impossible to completely control the properties innate to the metallic body because the resin or rubber is a complement to the metallic bodyO To answer the purpose 9 therefore, the resin or rubber must be greater in mass than the metallic body whereby the rigidity of metal can no longer be effectively usedc In the latter case the main skeleton is of plastics so that it lacks in rigidity and the turntable causes damping action to swing the disc up and down, while causing a fear of troubling the tracing operation of stylus chip~
Further, being light in weight with regard to plastics9 its mass is small when the content of filler is less to lack in the inertia mass of said turntable thereby causing wow and flutter as in a turntable of metal plate~ ~urthermore, wooden articles have a great damping ratio but they come short of rigidityO
The object of the invention is to provide materials for acoustic machines and instruments of the kind described at the beginning of the specifica-tion9 said machines and instruments excluding the conventional demerits and having good performance~
The turntalbe according to the invention consists of a sintered ceramic body wherein porosity is more than 20% and the diameter of the pores is less than 300 microns on an average9 and at least part of the pores of said sintered body is impregnated with elastic materials such as rubber and/or resin . T~e great rigidity '~
and mass possessed by ceramic may serve for less sensitivity against vibration of the turntalbe and for quickly attenuating the vibration thanks to the pores of ceramicO In the ceramic fit for the material of the acoustic machines and instruments according to the invention, the greater in rigidity the betterO
However, the allowable lower limit o~ the rigidity will be a Knoop hardness of more than 500 to fall under a range in which the strain by vibration does ' 10 not badly affects the sound effectsO This means that materials harder than ceramic or glass can be usedO
Further9 preferably the ratio of the pores which attenuate the damping ratio of vibration as quickly as possible is more than 20% porosity9 and the porosity of less than 20% will have less effect because it can-not sufficiently form pores included between crystal particles of ceramic in order to promptly decrease the vibration added to,the ceramic body. Accordi.nglys the less in the size of pores the wider they disperse so that the pores can be included more between the crystals and particles of ceramic to increase the attenuating properties of inside vibrationp but ceramic having an average pore diameter of less than 300 microns can satisfy these requirements and it is effective for increasing the damping ratio of vibration to impregnate the interior of the pores of ceramac having said ~ores with elastic substances such as rubber and/or resin in place of air.
That is, the rubber or resin is acti~e for enclosing the vibration whiçh ~Jas subject to the crystals or particles of.cera~ic to be a rigid body, into the 1 1 2 ~ 2 crystals or perticles 9 thereby attenuating the vibra-tionO The i~pregnation ~.ay not necessarily be carried out over the entirc pores 9 and it may be restricted to the upper f ace and lower f ace of the material to be treated or non-uniformly dispersed in its entiretyO ~dvantageously~ the turntable which is impregnated with rubber or resin at its upper face will not require a turnt&ble sheet made of rubberO
The invention will now be described more in detail 9 by way o-. examples 9 with reference to a turn-tableO
- Ceramic material is added with kaolin of more than 10% and then wet mixed with a small amount of combustible material and water~ The mixture is moulded by pressing such as under hydraulic pressure9 air pressure, oil pressure or friction9 and after drying it is sintesed in a sintering furnaceO After cooling the sintered article, its surface is faced thereby grinding and processing it to a,desired extent of preciseness of dimension and shapeO The mixed combustible materials are effective for forming pores9 and there are used wax, fine powder of wood9 starch9 wheat powder and the likeO
Impregnation of the elastic substances may be carried out in a liquid state of said substances9 such as latex of natural or artificial rubber besides a carbon disulIide solutionlo~ rubber9 an alcohol solution of resin or the like 9 by either coating it onto the surface of turntable or dipping the turntakle in it thereafter dryingO
Mixing examples and the properties of the sintered pieces of ceramic produced with said mixing are now described hereunderO
(a) Alumina (250 ~) 87%
Kaolin 13%
Porosity 32%
Average pore diameter 150 Bulk specific gravity 2047 Hardness 2200 Knoop (b) Silicon carbide (125~) 85%
Kaolin 15%
Porosity 31%
Average pore diameter 45~
Bulk specific gravity 2004 Hardness 2400 Knoop As a mode of working of the invention, a test listening was carried out by acoustic specialists by using a disc turntable in which a turntable sheet made of baked ceramic impregnated withsilicon rubber was adhered onto a conventional turntable made of alumi-nium die casting, with an adhesive. As a result, it was proved that compared with conventional aluminium die casting disc turntable with rubber sheet 9 there was scarcely resonance caused by mechanical vibration9 sound effects of high damping effect were exerted9 and acoustic properties thanks to the rigidity and porosity of ceramic are very prominent, said properties being a technical idea of the inventionO
_
Claims
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A structural material for acoustic machines and instruments, which consists of a sintered ceramic body wherein porosity is more than 20% and the diameter of pores is less than 300 microns on an average and at least part of pores is impregnated with rubber and/or resin.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8768578A JPS5515147A (en) | 1978-07-20 | 1978-07-20 | Structure material for sound equipment |
| JP87685/78 | 1978-07-20 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1129269A true CA1129269A (en) | 1982-08-10 |
Family
ID=13921775
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA331,208A Expired CA1129269A (en) | 1978-07-20 | 1979-07-05 | Structural material for acoustic machines and instruments |
Country Status (14)
| Country | Link |
|---|---|
| JP (1) | JPS5515147A (en) |
| AU (1) | AU525975B2 (en) |
| BE (1) | BE877666A (en) |
| CA (1) | CA1129269A (en) |
| DE (1) | DE2927884C2 (en) |
| DK (1) | DK304879A (en) |
| FR (1) | FR2431742A1 (en) |
| GB (1) | GB2025925B (en) |
| IN (1) | IN151078B (en) |
| IT (1) | IT1121187B (en) |
| LU (1) | LU81531A1 (en) |
| NL (1) | NL7905657A (en) |
| NO (1) | NO152715C (en) |
| SE (1) | SE7905653L (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS56169991A (en) * | 1980-06-03 | 1981-12-26 | Onkyo Corp | Member for acoustic device |
| JPS6232738Y2 (en) * | 1980-12-21 | 1987-08-21 | ||
| JPS6066182U (en) * | 1983-10-13 | 1985-05-10 | オンキヨー株式会社 | speaker box |
| JPS6068780U (en) * | 1983-10-15 | 1985-05-15 | オンキヨー株式会社 | speaker stand |
| JPS6068783U (en) * | 1983-10-15 | 1985-05-15 | オンキヨー株式会社 | speaker cabinet |
| DE3581300D1 (en) * | 1984-03-28 | 1991-02-21 | Reinhard Friedrich Hering | METHOD FOR THE ELASTOMER COATING OF MINERAL MATERIALS AND PRODUCT PRODUCED BY THIS METHOD. |
| EP0196865B1 (en) * | 1985-03-27 | 1990-09-12 | Ibiden Co, Ltd. | Electronic circuit substrates |
| NL1001183C2 (en) * | 1995-09-13 | 1997-03-20 | Tno | Exhaust device for a turbine engine. |
| DE202013000358U1 (en) * | 2013-01-15 | 2013-02-27 | Rüdiger Wichmann | Turntable pad for record player |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1072543B (en) * | 1959-12-31 | Metallgesellschaft Aktiengesell schaft, Frankfurt/M | Porous filter bodies and process for their manufacture | |
| DE1027582B (en) * | 1953-08-31 | 1958-04-03 | Dynamidon Werk Engelhorn & Co | Process for the production of highly refractory bricks |
| BE795941A (en) * | 1972-03-03 | 1973-08-27 | Siemens Ag | HIGH POROSITY PERMEABLE CERAMIC SUPPORT, IN PARTICULAR FOR CATALYSTS AS WELL AS ITS PREPARATION PROCESS |
| JPS5265418A (en) * | 1975-11-27 | 1977-05-30 | Pioneer Electronic Corp | Sound insulator |
| JPS52108111A (en) * | 1976-03-08 | 1977-09-10 | Sanyo Electric Co Ltd | Diaphragm for speaker |
| DE2627912C3 (en) * | 1976-06-22 | 1979-10-04 | Institut Vysokich Temperatur Akademii Nauk Ssr, Moskau | Porous high temperature construction material |
-
1978
- 1978-07-20 JP JP8768578A patent/JPS5515147A/en active Pending
-
1979
- 1979-06-27 SE SE7905653A patent/SE7905653L/en not_active Application Discontinuation
- 1979-06-27 IN IN659/CAL/79A patent/IN151078B/en unknown
- 1979-07-04 GB GB7923241A patent/GB2025925B/en not_active Expired
- 1979-07-05 AU AU48673/79A patent/AU525975B2/en not_active Ceased
- 1979-07-05 CA CA331,208A patent/CA1129269A/en not_active Expired
- 1979-07-11 DE DE2927884A patent/DE2927884C2/en not_active Expired
- 1979-07-12 BE BE0/196274A patent/BE877666A/en not_active IP Right Cessation
- 1979-07-18 NO NO792386A patent/NO152715C/en unknown
- 1979-07-19 IT IT09494/79A patent/IT1121187B/en active
- 1979-07-19 DK DK304879A patent/DK304879A/en not_active Application Discontinuation
- 1979-07-19 LU LU81531A patent/LU81531A1/en unknown
- 1979-07-20 NL NL7905657A patent/NL7905657A/en not_active Application Discontinuation
- 1979-07-20 FR FR7918763A patent/FR2431742A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| NO152715C (en) | 1985-11-13 |
| GB2025925B (en) | 1982-09-15 |
| NL7905657A (en) | 1980-01-22 |
| DK304879A (en) | 1980-01-21 |
| DE2927884A1 (en) | 1980-01-31 |
| FR2431742A1 (en) | 1980-02-15 |
| GB2025925A (en) | 1980-01-30 |
| JPS5515147A (en) | 1980-02-02 |
| NO152715B (en) | 1985-07-29 |
| AU525975B2 (en) | 1982-12-09 |
| LU81531A1 (en) | 1979-10-31 |
| FR2431742B1 (en) | 1984-09-07 |
| IT1121187B (en) | 1986-03-26 |
| DE2927884C2 (en) | 1982-06-09 |
| SE7905653L (en) | 1980-01-21 |
| IT7909494A0 (en) | 1979-07-19 |
| IN151078B (en) | 1983-02-19 |
| BE877666A (en) | 1979-11-05 |
| AU4867379A (en) | 1980-01-24 |
| NO792386L (en) | 1980-01-22 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |