Class / Patent application number | Description | Number of patent applications / Date published |
428846900 | Glass or ceramic substrate | 57 |
20080241603 | Magnetic Disk Glass Substrate - A magnetic disk glass substrate including compressive stress layers at main surfaces and a tensile stress layer between the compressive stress layers formed by chemical strengthening. When the glass substrate has a thickness of less than 0.5 mm and the tensile stress layer has a thickness L and a tensile stress of Pt (kg/mm | 10-02-2008 |
20080268295 | GLASS-CERAMICS - Glass-ceramics include SiO | 10-30-2008 |
20090092858 | PERPENDICULAR MAGNETIC RECORDING FILM MEDIUM AND METHOD OF MANUFACTURING THE SAME - The perpendicular magnetic recording medium of the present invention includes a substrate, a non-magnetic layer, a ferromagnetic layer and an antiferromagnetic oxide. The non-magnetic layer is formed on the substrate and the ferromagnetic layer is formed on the non-magnetic layer. The antiferromagnetic oxide is formed in the ferromagnetic layer after the perpendicular magnetic recording medium is annealed by an annealing process. An exchange coupling interaction between the antiferromagnetic oxide and the ferromagnetic materials is introduced. | 04-09-2009 |
20090142625 | MAGNETIC RECORDING MEDIUM, PRODUCTION PROCESS THEREOF, AND MAGNETIC RECORDING AND REPRODUCING APPARATUS - The present invention provides a magnetic recording medium which enables improvement of the layer quality of magnetic layer grown on the surface of a soft magnetic underlayer by conducting excellent control of crystal orientation by imparting an optimal half-width of the Rocking curve (Δθ50), as well as obtainment of SNR that suppresses generation of TA and enables realization of high-density recording. The magnetic recording medium includes a soft magnetic underlayer, an orientation control layer, a perpendicular magnetic recording layer, and a protective layer, which are disposed on top of a non-magnetic substrate; wherein the magnetic anisotropy ratio (Hmr/Hmc) of the soft magnetic underlayer is 1 or less, and Δθ50 is 1 to 6 degrees. The soft magnetic underlayer is formed on the primary surface of the non-magnetic substrate where the primary surface has been polished one substrate at a time by a sheet-type texture processing device using polishing tape and a slurry containing colloidal silica abrasive grain. | 06-04-2009 |
20090142626 | GLASS SUBSTRATE FOR MAGNETIC DISK AND MAGNETIC DISK APPARATUS - A glass substrate for a magnetic disk satisfies Ra | 06-04-2009 |
20090148724 | Glass Substrate for Magnetic Recording Medium and Magnetic Recording Medium - A glass substrate for a magnetic recording medium, having a chamfer face between the surface of the substrate for forming thereon a film comprising a magnetic layer, and the outer peripheral end face (straight face) of the substrate, wherein an R face having a curvature of 0.013 to 0.080 mm is provided between the data face and the chamfer face of the glass substrate. | 06-11-2009 |
20090220824 | Glass substrate for information recording medium and magnetic information recording medium to which the glass substrate is applied - Disclosed are a glass substrate for an information recording medium, having excellent scratch resistance and a light weight and having high fracture toughness, the glass substrate having a fragility index value, measured in water, of 12 μm | 09-03-2009 |
20090239101 | GLASS SUBSTRATE AND THERMAL-ASSISTED MAGNETIC RECORDING DISK - A plurality of recording magnetization portions is arranged in a concentric manner around a center of a glass substrate. A plurality of non-magnetization portion having a thermal conductivity lower than that of the recording magnetization portions is formed each between adjacent recording magnetization portions along a circumferential direction on a main surface of the glass substrate. A mean squared roughness of a surface of an area where each of the non-magnetization portions is formed is equal to or smaller than 1 nanometer. | 09-24-2009 |
20090239102 | GLASS FOR DATA STORAGE MEDIUM SUBSTRATE, GLASS SUBSTRATE FOR DATA STORAGE MEDIUM AND MAGNETIC DISK - To provide glass for a data storage medium substrate, whereby high heat resistance can be obtained. | 09-24-2009 |
20090252993 | GLASS SUBSTRATE FOR AN INFORMATION RECORDING MEDIUM, METHOD FOR MANUFACTURING A GLASS SUBSTRATE FOR AN INFORMATION RECORDING MEDIUM, AND AN INFORMATION RECORDING MEDIUM - Provided are a glass substrate for an information recording medium, which has both high strength and high flatness and can be manufactured at low cost, a method for manufacturing such glass substrate and an information recording medium using such glass substrate. The glass substrate for the information recording medium satisfies inequalities of 0.1≦(W1−W3)/W2≦5, where, W1 is an ion concentration at the center portion in the thickness direction of the glass substrate in a chemically reinforced region at the outer circumference end surface and the inner circumference end surface of the glass substrate and is the maximum value of K | 10-08-2009 |
20090324995 | GLASS SUBSTRATE FOR MAGNETIC DISK - There is provided a glass substrate for a magnetic disk in which a maximum height of bumps forming a roughness pattern at a period of smaller than 2 μm is 6 nm or lower in an annular area having a width of 30 μm on a main surface on which a magnetic recording area is formed, a number of bumps having a height of 3 nm or higher in a unit area having a circular arc length of 30 μm within the annular area is one or less, and a difference in arithmetic average roughness between unit areas within the annular area is 0.2 nm or smaller. | 12-31-2009 |
20100075180 | MAGNETIC RECORDING MEDIUM SUBSTRATE AND MANUFACTURING METHOD THEREOF, AND MAGNETIC RECORDING MEDIUM AND MANUFACTURING METHOD THEREOF - Provided is a magnetic recording medium substrate suitable for preparation of a DT medium and a patterned medium, and the magnetic recording medium substrate is possible to be of easy preparation of the DT medium and the patterned medium with no complicated processes. Disclosed is a magnetic recording medium substrate comprising a circular plate-shaped substrate made of a nonmagnetic base material, wherein a predetermined region of a surface of the substrate to form a magnetic film on the surface is more roughened than another region of the surface. When forming a magnetic film on this substrate, the magnetic film is formed in the region of the substrate surface, which is more roughened than the other region, to easily prepare the DT medium and the patterned medium. | 03-25-2010 |
20100136372 | GLASS SUBSTRATE FOR MAGNETIC DISK AND METHOD FOR PRODUCING THE SAME - The present invention relates to a method for producing a glass substrate for a magnetic disk, the method including a step of polishing a main surface of a circular glass plate while supplying a polishing slurry containing a polishing material, in which polishing is performed, after a polishing surface is subjected to dressing treatment, by using a polishing pad having: a first resin foam layer which forms the polishing surface, includes a resin foam having pores with a pore diameter of more than 20 μm and has a thickness of 400 μm or less; and a second resin foam layer which is provided between a platen for fixing the polishing pad and the first resin foam layer, includes a resin foam having pores with a pore diameter of 20 μm or less and has a thickness of 50 to 250 μm, and in which a total thickness of the first resin foam layer and the second resin foam layer is 550 μm or less, and a international rubber hardness degree of the polishing pad measured by the M method according to JIS K6253 is 40 IRHD or more. | 06-03-2010 |
20100209742 | METHOD OF MANUFACTURING A GLASS SUBSTRATE FOR A MAGNETIC RECORDING MEDIUM, A GLASS SUBSTRATE FOR A MAGNETIC RECORDING MEDIUM MANUFACTURED BY THE METHOD, AND A PERPENDICULAR MAGNETIC RECORDING MEDIUM - The present invention provides a method of manufacturing a glass substrate for a magnetic recording medium, the method allowing the surface roughness of the glass substrate being controlled easily and precisely in a stable state. The method comprises a step of finish polishing of polishing a surface of the glass substrate with a slurry containing two types of colloidal silica particles having different diameters and mixed in a predetermined ratio. | 08-19-2010 |
20100215993 | GLASS SUBSTRATE FOR INFORMATION RECORDING MEDIUM AND METHOD FOR PRODUCING THE SAME - There is provided a glass substrate which has the properties required in the use as a substrate for an information recording medium of the next generation such as a perpendicular magnetic recording system, and can be applied as a substrate for an information recording medium of the next generation particularly on the premise of using the glass substrate in a dynamic environment. More particularly, there is provided a glass substrate for an information recording medium which has sufficiently high surface hardness, has a good balance between specific gravity and mechanical strength, and has high strength to withstand high speed rotation or drop impact, and which can be produced with a high productivity adequate for a direct press method, without the occurrence of bubbles in the glass blank or reboil upon pressing even if arsenic components or antimony components are not substantially used. A glass substrate for an information recording medium, includes, as expressed in terms of percent by mass on the oxide basis: 52 to 67% of SiO | 08-26-2010 |
20100247977 | SUBASTRATE FOR A MAGNETIC DISK AND METHOD OF MANUFACTURING THE SAME - In a magnetic disk substrate having first and second chamfered faces respectively connecting between first and second main surfaces opposite to each other and an edge face located between the first and second main surfaces, the ranges of the first and second chamfered faces are specified. Specifically, the distance a from a first boundary portion being a boundary between the first main surface and the first chamfered face to a point of intersection between the first main surface and an extended line of the edge face and the distance b from a second boundary portion being a boundary between the second main surface and the second chamfered face to a point of intersection between the second main surface and an extended line of the edge face are set to satisfy a/b≧1.6. | 09-30-2010 |
20100255350 | GLASS FOR INFORMATION RECORDING MEDIUM SUBSTRATE, GLASS SUBSTRATE FOR INFORMATION RECORDING MEDIUM AND MAGNETIC DISK - To provide glass for an information recording medium substrate, which is excellent in the acid resistance and weather resistance. | 10-07-2010 |
20100266874 | METHOD OF SURFACE-FINISHING GLASS SUBSTRATE FOR MAGNETIC DISKS AND GLASS SUBSTRATE FOR MAGNETIC DISKS - An inner peripheral edge of a toroidal glass substrate for a magnetic disk is subjected to mechanical polishing in such a manner that the surface roughness is no greater than 9 nm in terms of Rmax. Then, the inner peripheral edge is subjected to chemical polishing to remove at least 2 μm of a surface layer. The inner peripheral edge has a non-conventional mirror-finished surface obtained by mechanical polishing. Thus, sufficient ring strength is obtained even when the chemical polishing depth is smaller than in the past. A polishing depth of less than 5 μm is sufficient. | 10-21-2010 |
20100330396 | GLASS FOR INFORMATION RECORDING MEDIA SUBSTRATE, GLASS SUBSTRATE FOR MAGNETIC DISK AND MAGNETIC DISK - To provide a glass for an information recording media substrate, which is excellent in weather resistance. | 12-30-2010 |
20110064971 | GLASS SUBSTRATE MANUFACTURING METHOD, GLASS SUBSTRATE POLISHING METHOD, GLASS SUBSTRATE POLISHING APPARATUS AND GLASS SUBSTRATE - A polishing apparatus, includes: a motor; and a controlling unit configured to control the motor, wherein: a glass substrate is polished by causing the controlling unit to control a driving of the motor; and the controlling unit executes a controlling operation for controlling a polishing of the glass substrate, based on an electric power or an electric energy required for the driving of the motor. | 03-17-2011 |
20110086241 | GLASS FOR MAGNETIC RECORDING MEDIA SUBSTRATES, MAGNETIC RECORDING MEDIA SUBSTRATES, MAGNETIC RECORDING MEDIA AND METHOD FOR PREPARATION THEREOF - The provided are a glass for a magnetic recording medium substrate permitting the realization of a magnetic recording medium substrate affording good chemical durability and having an extremely flat surface, a magnetic recording medium substrate comprised of this glass, a magnetic recording medium equipped with this substrate, and methods of manufacturing the same. Glasses for a magnetic recording medium substrate are, glass I comprised of an oxide glass, comprising, denoted as mass percentages:
| 04-14-2011 |
20110111263 | GLASS SUBSTRATE FOR INFORMATION RECORDING MEDIUM AND INFORMATION RECORDING MEDIUM - A glass substrate for information recording medium, said glass substrate being composed of an alminosilicate glass containing 60-75% by mass of SiO | 05-12-2011 |
20110123832 | GLASS FOR MAGNETIC RECORDING MEDIUM SUBSTRATE, MAGNETIC RECORDING MEDIUM SUBSTRATE AND METHOD OF MANUFACTURING THE SAME, AND MAGNETIC RECORDING MEDIUM - An aspect of the present invention relates to glass for a magnetic recording medium substrate, which comprises, denoted as molar percentages, 50 to 75 percent of SiO | 05-26-2011 |
20110123833 | GLASS SUBSTRATE FOR INFORMATION RECORDING MEDIUM AND MAGNETIC DISK - To provide a glass for an information recording medium substrate, which is excellent in weather resistance. | 05-26-2011 |
20110123834 | MAGNETIC RECORDING MEDIUM GLASS SUBSTRATE AND METHOD OF MANUFACTURING THE SAME - An abrasion brush in which a width of each of bristle implanting portions is 1.1 to 2.2 times a stack width of stacked glass substrates (a thickness of each of the glass substrates when the glass substrates are stacked without using a spacer. or a sum of the thickness of the glass substrates and a spacer when the glass substrates are stacked using spacers) is used for an inner periphery end surface polishing of a magnetic recording medium glass substrate. By performing the inner periphery end surface polishing using the abrasion brush, scratches remaining in a chamfering portion of the glass substrate can be removed reliably with a high productivity, and it is possible to provide the magnetic recording medium glass substrate without pit defects in the chamfering portion. | 05-26-2011 |
20110129693 | MAGNETIC DISK GLASS SUBSTRATE - A magnetic disk glass substrate including compressive stress layers at main surfaces and a tensile stress layer between the compressive stress layers formed by chemical strengthening. When the glass substrate has a thickness of less than 0.5 mm and the tensile stress layer has a thickness L and a tensile stress of Pt (kg/mm | 06-02-2011 |
20110135964 | CRYSTALLIZED GLASS SUBSTRATE FOR INFORMATION RECORDING MEDIUM AND METHOD OF PRODUCING THE SAME - To provide a substrate for information recording medium having various properties, in particular higher fracture toughness, required for application of the substrate for information recording medium of the next generation such as perpendicular magnetic recording system, etc. and a material with excellent workability for such purpose. A crystallized glass substrate for information recording medium, consisting of a crystallized glass which comprises one or more selected from RAl | 06-09-2011 |
20110151282 | METHOD FOR MANUFACTURING GLASS SUBSTRATE FOR DATA STORAGE MEDIUM AND GLASS SUBSTRATE - The present invention relates to a method for manufacturing a glass substrate for data storage mediums, the method including a chemical strengthening treatment step of dipping a glass for a substrate in a mixed molten salt to form a compressive layer on front and back surfaces of the glass for a substrate, in which the glass for a substrate contains a lithium ion as an alkali component, the mixed molten salt contains sodium nitrate, potassium nitrate and lithium nitrate, an amount of lithium nitrate being from 1 to 6% by mass, and the glass for a substrate is dipped in the mixed molten salt at a treatment temperature of 325° C. or more and 475° C. or less for a treatment time of 30 minutes or less, under the requirement satisfying the following formula: 1900≦T×log(t | 06-23-2011 |
20110159318 | GLASS SUBSTRATE FOR INFORMATION RECORDING MEDIUM AND MAGNETIC DISK - A glass substrate for an information recording medium, comprising an alkali aluminosilicate glass, wherein the β—OH value is at least 0.20 mm | 06-30-2011 |
20110159319 | DISK-SHAPED GLASS SUBSTRATE AND METHOD OF MANUFACTURING DISK-SHAPED GLASS SUBSTRATE - A front end portion of a core drill is formed in an arc shape in which longitudinal cross-sectional portions have the same radius. A contact width of a cutting edge of the core drill which first comes in contact with a surface of the glass sheet is small for the surface of the glass sheet, and the contact width of the cutting edge which comes in contact with the surface of the glass sheet is gradually increased as the core drill is lowered. An annular cavity into which the front end portion of the core drill is inserted is formed on an upper surface of the stage on which the glass sheet is placed. The annular cavity is formed so that its cavity width in the radial direction is wider than a drill width of the core drill. | 06-30-2011 |
20110159320 | GLASS SUBSTRATE FOR MAGNETIC DISK AND MANUFACTURING METHOD THEREOF - The present invention provides a glass substrate for magnetic disk in which surface irregularity of a principal surface is suppressed and a method for efficiently manufacturing a glass substrate for magnetic disk. The method includes the steps of: forming a sheet glass material by performing press forming to molten glass, a principal surface of the sheet glass material having target flatness for the glass substrate for magnetic disk, the sheet glass material having a surface shape to be ground using a grinding abrasive grain; grinding the sheet glass material using a fixed abrasive grain; and polishing the sheet glass material using a loose abrasive grain, the sheet glass material having surface irregularity of the principal surface ground using the fixed abrasive grain. | 06-30-2011 |
20110159321 | GLASS SUBSTRATE FOR MAGNETIC DISK AND MANUFACTURING METHOD THEREOF - The present invention provides a method for efficiently manufacturing a glass substrate for magnetic disk having good accuracy of a surface irregularity and an impact resistance. The method includes the steps of: performing press forming to molten glass to prepare a sheet glass material, the sheet glass material having a roughness of the principal surface of 0.01 μm or less and target flatness of a glass substrate for magnetic disk; chemically strengthening the sheet glass material by dipping the sheet glass material in a chemically strengthening salt, thereby preparing a disk substrate; polishing the principal surfaces of the disk substrate. A thickness of the sheet glass material prepared in the press forming step is larger than a target thickness of the glass substrate for magnetic disk by a polishing quantity of the principal surface polishing step. | 06-30-2011 |
20110159322 | GLASS FOR CHEMICAL STRENGTHENING, SUBSTRATE FOR INFORMATION RECORDING MEDIA AND INFORMATION RECORDING MEDIA - A glass for use in chemical reinforcement for use in a substrate of an information recording medium, having a composition comprising, denoted as mol %: | 06-30-2011 |
20110189505 | METHOD FOR MANUFACTURING GLASS SUBSTRATE FOR MAGNETIC RECORDING MEDIUM - The present invention provides a method for lapping a glass substrate, including lapping a glass substrate having excellent maximum thickness deviation, and a method for manufacturing a glass substrate for a magnetic recording medium, including a step using the above-mentioned lapping method. | 08-04-2011 |
20110189506 | GLASS SUBSTRATE FOR MAGNETIC RECORDING MEDIUM, AND METHOD FOR MANUFACTURING THE SAME - The present invention relates to a glass substrate for a magnetic recording medium, which is a disk-shaped glass substrate for a magnetic recording medium having a circular hole at the center thereof, in which the glass substrate for a magnetic recording medium has an inner peripheral side surface, an outer peripheral side surface and both main surfaces, and the both main surfaces have parallelism of 3.2 μm or less in at least a recording and reproducing region thereof. | 08-04-2011 |
20110195279 | METHOD FOR MANUFACTURING GLASS SUBSTRATE FOR INFORMATION RECORDING MEDIUM, GLASS SUBSTRATE FOR INFORMATION RECORDING MEDIUM, AND MAGNETIC RECORDING MEDIUM - A method for manufacturing a glass substrate for an information recording medium, wherein the abrasive and foreign matters adhered on the glass substrate after the polishing step are surely removed without making the cleaning step complicated. The glass substrate is cleaned by scrubbing with water to which 0.5-5.0 mass % of hydrogen peroxide has been added as a cleaning solution. | 08-11-2011 |
20110268994 | GLASS SUBSTRATE FOR INFORMATION RECORDING MEDIUM, POLISHING COLLOIDAL SILICA SLURRY FOR MANUFACTURING THE SAME AND INFORMATION RECORDING MEDIUM - The present invention relates to a colloidal silica slurry used in a method for manufacturing a glass substrate for an information recording medium, the method including: a lapping step of lapping a main surface of a circular glass plate; a subsequent cerium oxide polishing step of polishing the main surface of the circular glass plate with a slurry containing a cerium oxide abrasive; and a colloidal silica polishing step of polishing the main surface of the circular glass plate with a slurry containing a colloidal silica abrasive after the cerium oxide polishing step, in which the colloidal silica abrasive has a BET average particle size determined by a BET specific surface area measuring method of 40 nm or less, and a smoothness index represented by a ratio (BET average particle size (nm)/Circularity) of the BET average particle size and a circularity indicated by 4·π·S/L | 11-03-2011 |
20120100397 | GLASS FOR SUBSTRATE, AND GLASS SUBSTRATE - To provide glass to be used for a substrate which is, as a substrate, less susceptible to surface roughening even if subjected to cleaning by means of a strongly acidic solution. | 04-26-2012 |
20120107647 | GLASS SUBSTRATE FOR MAGNETIC RECORDING MEDIUM AND MAGNETIC RECORDING MEDIUM - An aspect of the present invention relates to a glass substrate for a magnetic recording medium, which is comprised of glass comprising, denoted as molar percentages, 56 to 75 percent of SiO | 05-03-2012 |
20120183812 | Glass Substrate for Information Recording Media and Information Recording Medium - Provided are a glass substrate for information recording media wherein air bubbles can be sufficiently removed, and an information recording medium using the glass substrate. The glass substrate contains 65 to 90 mass % of SiO | 07-19-2012 |
20120244388 | GLASS SUBSTRATE FOR INFORMATION RECORDING MEDIA, PROCESS FOR ITS PRODUCTION, AND MAGNETIC RECORDING MEDIUM - A process for producing a glass substrate for information recording media, comprising lapping a glass disk made of low alkali aluminosilicate glass that contains no alkali metal oxide or contains alkali metal oxides in a total amount of less than 4 mol %, and subsequently polishing the glass disk by using a slurry that contains cerium oxide abrasives, characterized by cleaning the glass disk by using a cleaning liquid that contains sulfuric acid at a concentration of from 20 mass % to 80 mass % and hydrogen peroxide at a concentration of from 0.5 mass % to 10 mass % at a liquid temperature of from 50° C. to 100° C., and thereafter polishing the main surface of the glass disk, by using a slurry that contains colloidal silica abrasives. | 09-27-2012 |
20120276416 | MAGNETIC DISK SUBSTRATE, MAGNETIC DISK, AND MAGNETIC DISK DEVICE - It is an object to provide a magnetic disk substrate highly reliable to prevent the occurrence of crash failure even if a magnetic disk is rotated at high speed, and suitable for a hard disk that starts and stops by the load/unload method, and a magnetic disk using such a substrate. | 11-01-2012 |
20120282493 | GLASS SUBSTRATE FOR A MAGNETIC DISK, MAGNETIC DISK AND METHOD OF MANUFACTURING A MAGNETIC DISK - A glass substrate for a magnetic disk, wherein, in regions with respect to two places arbitrarily selected on a surface of the glass substrate on its central portion side relative to its outer peripheral end, a surface shape with a shape wavelength in a band of 60 to 500 μm is extracted from surface shapes in each of the regions and, assuming that a root mean square roughness Rq of the surface shape is given as a microwaviness Rq, the difference between the microwavinesses Rq of the regions is 0.02 nm or less or the difference between standard deviations of the microwavinesses Rq of the regions is 0.04 nm or less. | 11-08-2012 |
20130011695 | CRYSTALLIZED GLASS SUBSTRATE FOR INFORMATION RECORDING MEDIUM AND METHOD OF PRODUCING THE SAME - To provide a substrate for information recording medium having various properties, in particular higher fracture toughness, required for application of the substrate for information recording medium of the next generation such as perpendicular magnetic recording system, etc. and a material with excellent workability for such purpose. A crystallized glass substrate for information recording medium, consisting of a crystallized glass which comprises one or more selected from RAl | 01-10-2013 |
20130089754 | GLASS SUBSTRATE FOR MAGNETIC DISK AND MAGNETIC RECORDING MEDIUM - With regard to a glass substrate | 04-11-2013 |
20130101868 | Magnetic Recording Medium - A magnetic recording medium includes, in a main surface of a glass substrate ( | 04-25-2013 |
20130189546 | Method for Producing Glass Substrate for Information Storage Medium, and Information Storage Medium - For an information storage medium a glass substrate is produced in a method including the steps of: polishing a glass substrate with a polishing agent applied thereon; and subsequently, chemically strengthening a major surface of the glass substrate. The polishing agent contains cerium oxide at a purity equal to or larger than 99% by mass for CeO | 07-25-2013 |
20130260180 | GLASS SUBSTRATE FOR INFORMATION RECORDING MEDIUM AND METHOD FOR MANUFACTURING THE SAME - The present invention relates to a method for manufacturing a glass substrate for an information recording medium having a high level of cleanness and superior smoothness. The manufacturing method includes a step for washing a disk-shaped glass plate with an acid washing liquid, a step for removing at least part of a surface layer, which is formed on the surface of the glass plate, by performing grinding with diamond abrasion grains, and a step for washing the surface with a neutral or alkaline washing liquid. | 10-03-2013 |
20130316194 | MANUFACTURING METHOD OF GLASS BLANK FOR MAGNETIC DISK, MANUFACTURING METHOD OF GLASS SUBSTRATE FOR MAGNETIC DISK, GLASS BLANK FOR MAGNETIC DISK, GLASS SUBSTRATE FOR MAGNETIC DISK, AND MAGNETIC DISK - To provide a method for manufacturing a glass blank for magnetic disk and a method for manufacturing a glass substrate for magnetic disk, which are capable of producing a glass blank for magnetic disk having a good surface waviness by press forming, and a method for manufacturing a glass substrate for magnetic disk. A method for manufacturing a glass blank for magnetic disk, which includes a forming process of press-forming a lump of molten glass using a pair of dies, wherein in the forming process, press forming is performed using thermally equalizing means for reducing a difference in temperature in the press forming surface of the die during pressing of the molten glass. | 11-28-2013 |
20140065446 | METHOD FOR MANUFACTURING GLASS BLANK FOR MAGNETIC DISK, METHOD FOR MANUFACTURING GLASS SUBSTRATE FOR MAGNETIC DISK, GLASS BLANK FOR MAGNETIC DISK - A method for manufacturing a glass blank for magnetic disk and a method for manufacturing a glass substrate for magnetic disk are provided which are capable of producing a glass blank for magnetic disk having a good surface waviness by press forming. The method includes a forming process of press-forming a lump of molten glass using a pair of dies, wherein in the forming process, press forming is performed using thermally equalizing means for reducing a difference in temperature in the press forming surface of the die during pressing of the molten glass. | 03-06-2014 |
20140141285 | CRYSTALLIZED GLASS AND CRYSTALLIZED GLASS SUBSTRATE FOR INFORMATION RECORDING MEDIUM - It is an object of the present invention to provide a crystallized glass which has various properties required for employing the substrate for information recording medium of the next generation, and also has significantly low specific gravity; and a crystallized glass substrate for information recording medium. A crystallized glass containing, as a crystal phase, one or more selected from RAl | 05-22-2014 |
20140220386 | SUBSTRATE FOR MAGNETIC DISK AND MAGNETIC DISK - The shape and number of surface defects are controlled so that the occurrence of failure is suppressed in an HDD device in which a magnetic head with a very small flying height, such as a DFH head, is mounted. | 08-07-2014 |
20140234667 | GLASS SUBSTRATE FOR INFORMATION RECORDING MEDIUM AND METHOD FOR MANUFACTURING THE SAME - The present invention relates to a method for manufacturing a glass substrate for an information recording medium having a high level of cleanness and superior smoothness. The manufacturing method includes a step for washing a disk-shaped glass plate with an acid washing liquid, a step for removing at least part of a surface layer, which is formed on the surface of the glass plate, by performing grinding with diamond abrasion grains, and a step for washing the surface with a neutral or alkaline washing liquid. | 08-21-2014 |
20140302346 | GLASS FOR USE AS SUBSTRATE FOR INFORMATION RECORDING MEDIUM, SUBSTRATEFOR INFORMATION RECORDING MEDIUM AND INFORMATION RECORDING MEDIUM, ANDTHEIR PRODUCTION METHODS - According to one aspect of the present invention, provided is glass for use in substrate for information recording medium, which comprises, denoted as molar percentages, a total of 70 to 85 percent of SiO | 10-09-2014 |
20150118522 | METHOD OF FABRICATING A GLASS MAGNETIC HARD DRIVE DISK PLATTER USING FILAMENTATION BY BURST ULTRAFAST LASER PULSES - A non-ablative method and apparatus for making an economical glass hard disk (platter) for a computer hard disk drive (HDD) using a material machining technique involving filamentation by burst ultrafast laser pulses. Two related methods disclosed, differing only in whether the glass substrate the HDD platter is to be cut from has been coated with all the necessary material layers to function as a magnetic media in a computer's hard drive. Platter blanks are precisely cut using filamentation by burst ultrafast laser pulses such that the blank's edges need not be ground, the platter's geometric circularity need not be corrected and there is no need for further surface polishing. Thus the platters can be cut from raw glass or coated glass. As a result, this method reduces the product contamination, speeds up production, and realizes great reductions in the quantity of waste materials and lower production costs. | 04-30-2015 |
20160005431 | GLASS SUBSTRATE FOR MAGNETIC DISK AND MAGNETIC DISK - A magnetic-disk glass substrate has a circular center hole, a pair of main surfaces and an edge surface. The edge surface has a side wall surface and chamfered surfaces interposed between the side wall surface and the main surfaces, and a roundness of an edge surface on an outer circumferential side is 1.5 μm or less. Also, a midpoint A between centers of two least square circle respectively derived from outlines in a circumferential direction respectively obtained at two positions spaced apart by 200 μm in a substrate thickness direction on the side wall surface on the outer circumferential side, and centers B and C respectively derived from a respective one of two chamfered surfaces on the outer circumferential side in the substrate thickness direction, are located such that a sum of respective distances between A and B, and A and C, is 1 μm or less. | 01-07-2016 |
20160254018 | GLASS SUBSTRATE FOR MAGNETIC DISK AND MAGNETIC DISK FOR HEAT ASSISTED MAGNETIC RECORDING | 09-01-2016 |