GB2153851A - Ferro-magnetic layer of magnetic recording media - Google Patents
Ferro-magnetic layer of magnetic recording media Download PDFInfo
- Publication number
- GB2153851A GB2153851A GB08501273A GB8501273A GB2153851A GB 2153851 A GB2153851 A GB 2153851A GB 08501273 A GB08501273 A GB 08501273A GB 8501273 A GB8501273 A GB 8501273A GB 2153851 A GB2153851 A GB 2153851A
- Authority
- GB
- United Kingdom
- Prior art keywords
- magnetic recording
- recording medium
- magnetic
- ferromagnetic metal
- angstroms
- 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.)
- Granted
Links
- 230000005291 magnetic effect Effects 0.000 title claims abstract description 74
- 230000005294 ferromagnetic effect Effects 0.000 title claims abstract description 27
- 239000013078 crystal Substances 0.000 claims abstract description 43
- 239000002184 metal Substances 0.000 claims abstract description 26
- 229910052751 metal Inorganic materials 0.000 claims abstract description 26
- 239000002245 particle Substances 0.000 claims abstract description 21
- 239000000758 substrate Substances 0.000 claims abstract description 16
- 239000002923 metal particle Substances 0.000 claims abstract description 6
- 238000005240 physical vapour deposition Methods 0.000 claims abstract description 3
- 238000001771 vacuum deposition Methods 0.000 claims description 17
- 238000000034 method Methods 0.000 claims description 4
- 229910052759 nickel Inorganic materials 0.000 claims description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 2
- 229910017052 cobalt Inorganic materials 0.000 claims description 2
- 239000010941 cobalt Substances 0.000 claims description 2
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 2
- 239000001301 oxygen Substances 0.000 claims description 2
- 229910052760 oxygen Inorganic materials 0.000 claims description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims 2
- 229910000990 Ni alloy Inorganic materials 0.000 claims 1
- ZGDWHDKHJKZZIQ-UHFFFAOYSA-N cobalt nickel Chemical compound [Co].[Ni].[Ni].[Ni] ZGDWHDKHJKZZIQ-UHFFFAOYSA-N 0.000 claims 1
- 239000010409 thin film Substances 0.000 abstract description 7
- 229910020630 Co Ni Inorganic materials 0.000 description 16
- 229910002440 Co–Ni Inorganic materials 0.000 description 16
- 230000004907 flux Effects 0.000 description 10
- 238000001704 evaporation Methods 0.000 description 5
- 229910045601 alloy Inorganic materials 0.000 description 4
- 239000000956 alloy Substances 0.000 description 4
- 230000008020 evaporation Effects 0.000 description 4
- 239000010408 film Substances 0.000 description 4
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 229910001882 dioxygen Inorganic materials 0.000 description 3
- 238000009826 distribution Methods 0.000 description 2
- 239000010419 fine particle Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 229920000139 polyethylene terephthalate Polymers 0.000 description 2
- 239000005020 polyethylene terephthalate Substances 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 1
- 229910000428 cobalt oxide Inorganic materials 0.000 description 1
- IVMYJDGYRUAWML-UHFFFAOYSA-N cobalt(ii) oxide Chemical compound [Co]=O IVMYJDGYRUAWML-UHFFFAOYSA-N 0.000 description 1
- 238000007772 electroless plating Methods 0.000 description 1
- 238000010894 electron beam technology Methods 0.000 description 1
- 238000009713 electroplating Methods 0.000 description 1
- 238000007733 ion plating Methods 0.000 description 1
- 239000000696 magnetic material Substances 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- -1 polyethylene terephthalate Polymers 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000007738 vacuum evaporation Methods 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/62—Record carriers characterised by the selection of the material
- G11B5/64—Record carriers characterised by the selection of the material comprising only the magnetic material without bonding agent
- G11B5/65—Record carriers characterised by the selection of the material comprising only the magnetic material without bonding agent characterised by its composition
- G11B5/658—Record carriers characterised by the selection of the material comprising only the magnetic material without bonding agent characterised by its composition containing oxygen, e.g. molecular oxygen or magnetic oxide
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/62—Record carriers characterised by the selection of the material
- G11B5/68—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent
- G11B5/70—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer
- G11B5/706—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material
- G11B5/70605—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material metals or alloys
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
- C23C14/225—Oblique incidence of vaporised material on substrate
- C23C14/226—Oblique incidence of vaporised material on substrate in order to form films with columnar structure
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/84—Processes or apparatus specially adapted for manufacturing record carriers
- G11B5/85—Coating a support with a magnetic layer by vapour deposition
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S100/00—Presses
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Metallurgy (AREA)
- Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Organic Chemistry (AREA)
- Magnetic Record Carriers (AREA)
Abstract
In a magnetic recording medium comprising a thin film type ferromagnetic metal layer formed by physical vapour deposition on a non-magnetic substrate (4), the ferromagnetic metal layer comprises columnar crystals (10) inclined relative to the substrate (4), each of the columnar crystals being formed of ferromagnetic metal particles (11) and oxide particles (12) of the ferromagnetic metal randomly distributed in the columnar crystal. The recording medium has improved signal to noise ratio. <IMAGE>
Description
SPECIFICATION
Magnetic recording media
This invention relates to magnetic recording media.
Recently, extensive study has been given to a thin film type magnetic recording medium produced by forming a ferromagnetic thin film having a thickness of hundreds of Angstroms to about one micron on a non-magnetic substrate by methods such as electroplating, electroless plating, ion plating, sputtering, and vacuum evaporation for the purpose of achieving a magnetic recording of high density. An obliquely incident vacuum deposition method as disclosed in US Patent No. US-A-3 342 632 is of special interest because it permits a magnetic recording medium having a high coercive force to be obtained, and various improvements and modifications thereto have been carried out. According to this obliquely incident vacuum deposition method, a vapour flow of magnetic metal to be deposited on a substrate is incident upon the substrate in a direction oblique thereto.However, in a magnetic recording medium having a magnetic recording layer in the form of a ferromagnetic thin film, a video signal output in a short wavelength range is not always high enough to be expected, and the noise level is high. Therefore, there has not been obtained a magnetic recording medium which exhibits a satisfactory signal to noise (S/N) ratio.
According to the present invention there is provided a magnetic recording medium comprising a non-magnetic substrate and a ferromagnetic metal layer formed on the substrate by physical vapour deposition, the ferromagnetic metal layer having columnar crystals inclined relative to the substrate, and each of the columnar crystals being formed of ferromagnetic metal particles and oxide particles of said ferromagnetic metal randomly distributed in the columnar crystal.
The invention will now be further described, by way of illustrative and non-limiting example, with reference to the accompanying drawing, in which:
Figure 1 is a schematic view of a vacuum deposition apparatus employed in manufacturing a magnetic recording medium embodying the present invention; and
Figure 2 is a schematic view of the sectional structure of a columnar crystal of a magnetic layer of a magnetic recording medium embodying the present invention.
In magnetic recording media embodying the present invention and described in more detail below, oxide particles of ferromagnetic metal are randomly distributed in a columnar crystal forming the thin film type magnetic recording layer, so that the ferromagnetic metal fine crystal forming the columnar crystal may be fractionised. Accordingly, the noise level is reduced in respect of electro-magnetic conversion characteristics, to provide a thin film type magnetic recording medium having a high S/N ratio.
The thin film type magnetic recording layer is composed of an aggregate of the columnar crystal structures, and each of the columnar crystal structures if formed of a random distribution of ferromagnetic metal particles and oxide particles of the ferromagnetic metal.
In the magnetic recording media embodying the present invention, the noise level is reduced and the S/N ratio is improved. The reason why the noise level is reduced by the random distribution of the oxide particles of the ferromagnetic metal as an evaporating substance in the columnar crystal structure is believed to be due to the fact that the grain size of the evaporated magnetic metal particles forming the columnar crystal is made small.
Fig. 1 is a schematic view of a vacuum deposition apparatus 1 that can be used in the manufacture of the magnetic recording media embodying the present invention. The vacuum deposition apparatus 1 is constituted by a vacuum chamber 2 enclosing a vacuum containing a predetermined amount of oxygen, a metal can 3 disposed in the vacuum chamber 2, a nonmagnetic substrate 4 fed from a supply reel 5 to a take-up reel 6 around the metal can 3, an evaporation source 7 of a magnetic metal (such as Co, Ni or an alloy thereof) arranged at a position opposite to the metal can 3 and spaced suitably downwardly therefrom, and a shutter 8 interposed between the metal can 3 and the evaporation source 7.In use, magnetic metal evaporated from the evaporation source 7 is obliquely deposited on the non-magnetic substrate 4 at a predetermined angle of incidence with the aid of the shutter 8 to form a ferromagnetic layer which might, typically, have a thickness of 300 to 10,000 Angstroms. As indicated above, the magnetic (ferromagnetic) metal may, for example, be Co, Ni or an alloy thereof. In the case of a Co-Ni alloy, the content of Ni is preferably not more than 30 atomic %.
Examples of magnetic recording media embodying the invention will now be described in detail.
Example 1 By means of the above-described vacuum deposition apparatus 1, Co-Ni alloy (80 atomic % of Co; 20 atomic % of Ni) was obliquely deposited on a non-magnetic substrate 4 of polyethylene terephthalate (PET) having a thickness of 10 microns under a pressure of 1 x 10 4
Torr created by introducing oxygen gas (02) at a rate of 100 cm3/min. The angle of incidence of vacuum deposition was 40 to 90 , and a hating means employed for the evaporation source 7 was an electron beam. In the above manner, a vacuum deposition tape was prepared.
Characteristics of the tape were as follows:
Thickness of Co-Ni vacuum deposition film: 1000 Angstroms
Magnetic characteristics:
Coercive force (Hc): 820 Oe
Saturation magnetic flux density (Bm): 6800 G
Residual magnetic flux density (Br): 4900 G
Rectangular ratio (Br/Bm): 0.72.
A cross section of the magnetic tape as obtained above and observed by means of a transmission electron microscope (TEM). It was observed from a bright image with the TEM that a magnetic layer as deposited on the substrate 4 comprised an aggregate of fine columnar crystals, and that all the columnar crystals were arranged at angles of 60 to 65 relative to the substrate. Further, the width of the columnar crystals was 50 to 100 Angstroms. It was observed from a dark image with the TEM that Co-Ni particles having a size of 50 to 100
Angstroms and Co-Ni oxide particles having a size of 30 to 70 Angstroms were distributed uniformly in each of the columnar crystals.
Fig. 2 is a schematic view of the sectional structure of a columnar crystal forming the magnetic layer of the vacuum deposition tape of Example 1. In Fig. 2, reference numeral 10 designates the columnar crystal, the width of which was 50 to 100 Angstroms; reference numeral 11 designates the Co-Ni particles, the size of which was 50 to 100 Angstroms; and reference numeral 12 designates the Co-Ni oxide particles, the size of which was 30 to 70
Angstroms.
Comparison Example 1 A vacuum deposition tape was prepared under the same conditions as in Example 1, except that the pressure was set to 1 X 10-5 Torr with no oxygen gas introduced, and the angle of incidence was set to 70 to 90". Characteristics of the magnetic tape prepared above were as follows:
Thickness of Co-Ni vacuum deposition film: 1000 Angstroms
Magnetic characteristics:
Coercive force (Hc): 800 Oe
Saturation magnetic flux density (Bm): 6900 G
Residual magnetic flux density (Br): 6280 G
Rectangular ratio (Br/Bm):O.91 Observations of the magnetic layer by means of a TEM, in the same manner as in Example 1, showed that there was no uniformly distributed structure comprising metal partaicles and metal oxide particles as observed in Example 1.
Example 2
A vacuum deposition tape was prepared under the same conditions as in Example 1, except that Co (100%) was used as a magnetic material. Characteristics of the magnetic tape prepared as above were as follows:
Thickness of Co vacuum deposition film: 1000 Angstroms
Magnetic characteristics:
Coercive force (Hc): 910 Oe
Saturation magnetic flux density (Bm): 7300 G
Residual magnetic flux density (Br): 5300 G
Rectangular ratio (Br/Bm): 0.73
Although no sectional structure of a columnar crystal of the magnetic layer in Example 2 is shown in the drawings, the structure is similar to that shown in Fig. 2 for Example 1. That is, it is a randomly distributed structure of Co particles and CoO particles. Further, the sizes of the crystal and of the particles were similar to those in Example 1. That is, the size of the Co particles was 50 to 100 Angstroms; the size of the CoO particles was 30 to 70 Angstroms; and the width of the columnar crystal was 50 to 100 Angstroms.
Comparison Example 2
A vacuum deposition tape was prepared under the same conditions as in Example 2, except that the pressure was set to 1 X 10-5 Torr with no oxygen gas introduced, and that the angle of
incidence was set to 70 to 90 . Characteristics of the magnetic tape prepared were as follows:
Thickness of Co vacuum deposition film: 1000 Angstroms
Magnetic characteristics:
Coercive force (Hc): 900 Oe
Saturation magnetic flux density (Bm): 7500 G
Residual magnetic flux density (Br): 6800 G
Rectangular ratio (Br/Bm): 0.91
Observation by means of the TEM showed that there was no uniformly distributed structure comprising cobalt particles and cobalt oxide particles.
A comparison of electromagnetic conversion characteristics of magnetic tapes prepared in accordance with the above Examples and Comparison Examples is given in the following table.
The table shows an output and a noise level as measured by using a ferrite magnetic head having a gap length of 0.2 microns with a tape relative velocity set to 3.8 m/sec with a spectrum analyser. Each value in the table is indicated by comparison with use of a signal of 5
MHz, and a relative output and a S/N ratio of the tape in Comparison Example 1 were each defined as 0 dB.
Table
Output (5 MHz) S/N ratio
Example 1 - 1.5 dB + 2.0 dB
Example 2 - 0.8 dB + 3.9 dB
Comparison Example 1 0 dB 0 dB
Comparison Example 2 + 1.4 dB + 0.4 dB
First, comparing Example 1 with Comparison Example 1, both of which employ a Co-Ni magnetic layer, the coercive force Hc is substantially equal in both cases and the residual magnetic flux density Br and the rectangular ratio Br/Bm in Comparison Example 1 are superior. Further, it will be appreciated from the above table that the output of the tape in
Example 1 is lower than that in Comparison Example 1, and that the S/N ratio in Example 1 is superior to that in Comparison Example 1, resulting in reduction in noise.
It was observed by means of the TEM that fine crystals of Co-Ni and Co-Ni oxide are randomly distributed in the columnar crystal of the magnetic layer, as shown in Fig. 2, of
Example 1. On the contrary, the columnar crystal of the magnetic layer in Comparison Example 1 was formed of fine crystals of Co-Ni. In Example 1, the fine crystals of Co-Ni forming the columnar crystals are fractionised and formed into fine particles. On the contrary, in Comparison
Example 1, the fine crystals of Co-Ni are not fractionised by the Co-Ni oxide. Accordingly, as the particle size of the fine magnetic crystals of Co-Ni in Example 1 is smaller than that in
Comparison Example 1, noise is reduced in respect of electromagnetic conversion characteristics.
Comparing Example 2 with Comparison Example 2, both of which employ a Co magnetic layer, in similar manner the coercive force Hc is substantially equal in both cases, and the residual magnetic flux density Br and the rectangular ratio Br/Bm in Comparison Example 2 are superior. As will be apparent from the above table, the output in Example 2 is lower than that in
Comparison Example 2, and the S/N ratio in Example 2 is superior to that in Comparison
Example 2, resulting in reduction in noise.
It was observed by means of the TEM that fine crystals of Co and Co oxide are randomly distributed in the columnar crystal of the magnetic layer in Example 2. On the contrary, the columnar crystal of the magnetic layer in Comparison Example 2 was formed of fine crystals of
Co. Further, in Example 2, the fine crystals of Co forming the columnar crystal are fractionised and formed into fine particles. On the contrary, in Comparison Example 2, the fine crystals of Co are not fractionised by the Co oxide. Accordingly, similarly in Example 2, the particle size of the fine magnetic crystals of Co is smaller than that in Comparison Example 2, thus reducing noise in respect of electro-magnetic characteristics.
Claims (10)
1. A magnetic recording medium comprising a non-magnetic substrate and a ferromagnetic metal layer formed on the substrate by physical vapour deposition, for ferromagnetic metal layer having columnar crystals inclined relative to the substrate, and each of the columnar crystals being formed of ferromagnetic metal particles and oxide particles of said ferromagnetic metal randomly distributed in the columnar crystal.
2. A magnetic recording medium according to claim 1, wherein the ferromagnetic metal is cobalt.
3. A magnetic recording medium according to claim 1, wherein the ferromagnetic metal is a cobalt-nickel alloy containing not more than 30 atomic percent of nickel.
4. A magnetic recording medium according to claim 1, claim 2 or claim 3, wherein the ferromagnetic metal layer is deposited by a vacuum deposition process in an oxygen-containing atmosphere.
5. A magnetic recording medium according to any one of the preceding claims, wherein the ferromagnetic metal layer has a thickness of between 300 and 10,000 Angstroms.
6. A magnetic recording medium according to any one of the preceding claims, wherein the columnar crystals have a width of between 50 and 100 Angstroms.
7. A magnetic recording medium according to any one of the preceding claims, wherein the ferromagnetic metal particles have a grain size of between 50 and 100 Angstroms
8. A magnetic recording medium according to any one of the preceding claims, wherein the oxide particles have a grain size of between 30 and 70 Angstroms.
9. A magnetic recording medium substantially as set forth in Example 1 or Example 2 above.
10. A magnetic recording medium substantially as herein described with reference to Fig. 2 of the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59009169A JPS60154323A (en) | 1984-01-20 | 1984-01-20 | Magnetic recording medium |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8501273D0 GB8501273D0 (en) | 1985-02-20 |
| GB2153851A true GB2153851A (en) | 1985-08-29 |
| GB2153851B GB2153851B (en) | 1987-06-03 |
Family
ID=11713089
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08501273A Expired GB2153851B (en) | 1984-01-20 | 1985-01-18 | Ferro-magnetic layer of magnetic recording media |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS60154323A (en) |
| KR (1) | KR920008414B1 (en) |
| DE (1) | DE3501561C2 (en) |
| FR (1) | FR2558631B1 (en) |
| GB (1) | GB2153851B (en) |
| NL (1) | NL192409C (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0156625A2 (en) * | 1984-03-22 | 1985-10-02 | Toray Industries, Inc. | Vertical magnetic recording medium and process for preparation thereof |
| GB2202866A (en) * | 1987-03-25 | 1988-10-05 | Sony Corp | Magnetic recording media |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2639065B2 (en) * | 1989-03-10 | 1997-08-06 | 松下電器産業株式会社 | Manufacturing method of magnetic recording media |
| FR2713360B1 (en) * | 1993-12-01 | 1996-03-08 | Aerospatiale | Centralized control system for an industrial installation. |
| US7241519B2 (en) | 2003-07-07 | 2007-07-10 | Sony Corporation | Magnetic recording medium with columar magnetic layer |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0023328A1 (en) * | 1979-07-18 | 1981-02-04 | Matsushita Electric Industrial Co., Ltd. | Metallic thin film magnetic recording medium |
| GB1599161A (en) * | 1976-07-15 | 1981-09-30 | Matsushita Electric Ind Co Ltd | Magnetic recording medium and method of making the same |
| EP0053811A1 (en) * | 1980-12-05 | 1982-06-16 | Matsushita Electric Industrial Co., Ltd. | Magnetic recording media |
| GB2112666A (en) * | 1981-11-12 | 1983-07-27 | Fuji Photo Film Co Ltd | Magnetic recording medium |
| GB2129832A (en) * | 1982-10-12 | 1984-05-23 | Sony Corp | Magnetic recording media |
| GB2133316A (en) * | 1982-12-25 | 1984-07-25 | Tdk Corp | Magnetic recording medium |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5629A (en) * | 1979-06-15 | 1981-01-06 | Ulvac Corp | Vacuum-evaporated film type magnetic recording substance and its manufacture |
| JPS573223A (en) * | 1980-06-03 | 1982-01-08 | Tdk Corp | Magnetic recording medium |
| JPS57152516A (en) * | 1981-03-16 | 1982-09-20 | Hitachi Maxell Ltd | Magnetic recording medium |
| JPS57152520A (en) * | 1981-03-17 | 1982-09-20 | Matsushita Electric Ind Co Ltd | Magnetic recording medium |
| JPS5814324A (en) * | 1981-07-17 | 1983-01-27 | Fuji Photo Film Co Ltd | Magnetic recording medium |
| JPS5841443A (en) * | 1981-09-04 | 1983-03-10 | Fuji Photo Film Co Ltd | Manufacture of magnetic recording medium |
| JPS5883327A (en) * | 1981-11-12 | 1983-05-19 | Fuji Photo Film Co Ltd | Magnetic recording medium |
-
1984
- 1984-01-20 JP JP59009169A patent/JPS60154323A/en active Granted
-
1985
- 1985-01-15 NL NL8500085A patent/NL192409C/en not_active IP Right Cessation
- 1985-01-18 KR KR1019850000284A patent/KR920008414B1/en not_active IP Right Cessation
- 1985-01-18 DE DE3501561A patent/DE3501561C2/en not_active Expired - Lifetime
- 1985-01-18 GB GB08501273A patent/GB2153851B/en not_active Expired
- 1985-01-18 FR FR858500746A patent/FR2558631B1/en not_active Expired - Lifetime
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1599161A (en) * | 1976-07-15 | 1981-09-30 | Matsushita Electric Ind Co Ltd | Magnetic recording medium and method of making the same |
| EP0023328A1 (en) * | 1979-07-18 | 1981-02-04 | Matsushita Electric Industrial Co., Ltd. | Metallic thin film magnetic recording medium |
| EP0053811A1 (en) * | 1980-12-05 | 1982-06-16 | Matsushita Electric Industrial Co., Ltd. | Magnetic recording media |
| GB2112666A (en) * | 1981-11-12 | 1983-07-27 | Fuji Photo Film Co Ltd | Magnetic recording medium |
| GB2129832A (en) * | 1982-10-12 | 1984-05-23 | Sony Corp | Magnetic recording media |
| GB2133316A (en) * | 1982-12-25 | 1984-07-25 | Tdk Corp | Magnetic recording medium |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0156625A2 (en) * | 1984-03-22 | 1985-10-02 | Toray Industries, Inc. | Vertical magnetic recording medium and process for preparation thereof |
| EP0156625A3 (en) * | 1984-03-22 | 1986-12-30 | Toray Industries, Inc. | Vertical magnetic recording medium and process for preparation thereof |
| US4888211A (en) * | 1984-03-22 | 1989-12-19 | Toray Industries, Inc. | Process for preparation of vertical magnetic recording medium |
| GB2202866A (en) * | 1987-03-25 | 1988-10-05 | Sony Corp | Magnetic recording media |
| US4939046A (en) * | 1987-03-25 | 1990-07-03 | Sony Corporation | Magnetic recording medium |
| GB2202866B (en) * | 1987-03-25 | 1991-07-03 | Sony Corp | Magnetic recording media |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2558631A1 (en) | 1985-07-26 |
| NL192409C (en) | 1997-07-04 |
| NL8500085A (en) | 1985-08-16 |
| KR920008414B1 (en) | 1992-09-28 |
| JPH0475577B2 (en) | 1992-12-01 |
| GB2153851B (en) | 1987-06-03 |
| JPS60154323A (en) | 1985-08-14 |
| FR2558631B1 (en) | 1992-09-18 |
| NL192409B (en) | 1997-03-03 |
| GB8501273D0 (en) | 1985-02-20 |
| DE3501561C2 (en) | 1995-08-31 |
| DE3501561A1 (en) | 1985-08-14 |
| KR850005665A (en) | 1985-08-28 |
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| Date | Code | Title | Description |
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| PE20 | Patent expired after termination of 20 years |
Effective date: 20050117 |