WO2013047189A1 - 情報記録媒体用ガラス基板および情報記録媒体 - Google Patents
情報記録媒体用ガラス基板および情報記録媒体 Download PDFInfo
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- WO2013047189A1 WO2013047189A1 PCT/JP2012/073192 JP2012073192W WO2013047189A1 WO 2013047189 A1 WO2013047189 A1 WO 2013047189A1 JP 2012073192 W JP2012073192 W JP 2012073192W WO 2013047189 A1 WO2013047189 A1 WO 2013047189A1
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- 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
- G11B5/73—Base layers, i.e. all non-magnetic layers lying under a lowermost magnetic recording layer, e.g. including any non-magnetic layer in between a first magnetic recording layer and either an underlying substrate or a soft magnetic underlayer
- G11B5/739—Magnetic recording media substrates
- G11B5/73911—Inorganic substrates
- G11B5/73921—Glass or ceramic substrates
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- the present invention relates to a glass substrate for information recording medium and an information recording medium.
- Information recording devices such as HDD (Hard Disk Drive) incorporate a disk-shaped information recording medium such as a magnetic disk or a magneto-optical disk.
- a disk-shaped glass substrate for information recording medium is used as the information recording medium.
- a magnetic thin film layer including a recording layer using properties such as magnetism, light, or magnetomagnetism is formed on the main surface of the glass substrate for information recording media.
- the magnetic thin film layer is magnetized by the magnetic head, whereby predetermined information is recorded on the information recording medium.
- the information recording medium rotates at high speed inside an information recording apparatus such as an HDD.
- the magnetic head flies over the magnetic thin film layer formed on the main surface of the glass substrate for the information recording medium.
- a DFH Dynamic Flying Height
- the distance between the magnetic head and the outermost surface of the information recording medium was an interval exceeding 10 nm.
- the radius length from the center of the information recording medium to the outer edge in the radial direction is 100%, even if the head running area is extended to an area exceeding 97% from the center, the magnetic head can be applied to the information recording medium. There was no problem in writing and reading information.
- the flying height tends to decrease as the recording density increases.
- the S / N ratio of the received signal at the magnetic head can be improved, and the recording density on the information recording medium can be increased.
- the flying height is 5 nm or less, in order to suppress contact between the outermost surface of the information recording medium and the magnetic head (so-called head crash phenomenon), the smoothness and flatness of the main surface of the glass substrate for information recording medium
- the demand for is increasing.
- the magnetic head enters the recording surface of the information recording medium from the retracted position, the magnetic head is easily affected by the disturbance of the air flow due to the shape of the outer peripheral end surface of the information recording medium, and the magnetic head is floated. It may be unstable (Grain door balanche).
- the flying of the magnetic head becomes unstable during the transition from the retracted position to the traveling position on the recording surface of the information recording medium, the flying of the magnetic head during traveling on the recording surface is adversely affected. As a result, the recording density on the information recording medium cannot be increased efficiently.
- JP 2011-000704 A Patent Document 1
- JP 2007-257811 A Patent Document 2
- flatness is also required in the vicinity of the outer edge of the information recording medium.
- the problem to be solved by the present invention is that when the magnetic head enters the recording surface of the information recording medium from the retracted position, the influence of air flow turbulence due to the shape of the area near the outer peripheral end surface of the information recording medium It is easy to receive and the floating of the magnetic head becomes unstable.
- An object of the present invention is to provide a glass substrate for an information recording medium and an information recording medium having a structure that is less likely to cause turbulence of the air flow.
- An information recording medium glass substrate is a disk-shaped information recording medium glass substrate used as an information recording medium of an information storage device and having a center of rotation, wherein the magnetic thin film layer is formed. And an outer peripheral end face located at an edge of the glass substrate for information recording medium.
- a point at the radial distance from the outer peripheral end face on the main surface is 1.2 mm and the radial distance from the outer peripheral end face
- the reference line is an extension line connecting points at a position of 0.75 mm, and the amount of deviation between the reference position and any selected position on the main surface in the direction in which the rotation axis passing through the rotation center extends is defined as
- the roll-off value at the first radial position where the radial distance from the outer peripheral end face is 0.55 mm is set as the first roll-off value, and the radial distance from the outer peripheral end face is zero.
- the roll-off value at the second radial position of 45 mm is defined as the second roll-off value, and the radial distance from the outer peripheral end surface is at the third radial position at 0.30 mm.
- the roll-off value is the third roll-off value
- the difference between the first roll-off value and the second roll-off value is the first roll-off change amount
- the second roll-off value and the third roll-off value are The first roll-off change amount and the second roll-off change amount satisfy the following condition 1 and condition 2, where
- condition 1 180 ⁇ ⁇ first roll-off change ⁇ 990 ⁇ ⁇ ⁇ ⁇ Condition 1 650 ⁇ ⁇ second roll-off change ⁇ 3700 ⁇ Condition 2
- condition 2 is 8108 ⁇ second roll-off change ⁇ 2480 ⁇ .
- condition 1 is 250 ⁇ ⁇ first roll-off change ⁇ 450 ⁇
- condition 2 is 950 ⁇ ⁇ second roll-off change ⁇ 1870 ⁇ .
- the glass substrate for information recording medium has an inclined surface having a width of 0.1 mm in the radial direction from the outer peripheral end surface in a region where the main surface and the outer peripheral end surface intersect.
- the radial distance from the outer peripheral end surface to the rotation center axis is 32.5 mm.
- the information recording medium based on this invention, it is an information recording medium used for an information storage device, and is a magnetic thin film provided on the main surface of the glass substrate for information recording medium described above and the glass substrate for information recording medium. And a layer.
- the recording density on one side of the main surface is 500 Gbit / inch 2 or more.
- the shape of the area near the outer peripheral end surface of the information recording medium when the magnetic head enters the recording surface of the information recording medium from the retracted position It is possible to provide a glass substrate for an information recording medium and an information recording medium having a structure that is less likely to cause air flow disturbance due to the above.
- FIG. 4 is a partial enlarged cross-sectional view taken along line IV in FIG. 2.
- the first roll-off value RO1 at the first radius position P1, the second roll-off value RO2 at the second radius position P2, and the third radius of the information recording media of Examples 1 to 6 and Comparative Example 1 It is a figure which shows the measured value of 3rd roll-off value RO3 in the position P3.
- FIG. 1 is a diagram showing a schematic configuration of an information recording apparatus 2 in the embodiment.
- a magnetic head 2D is disposed to face the information recording medium 1 that is rotationally driven in the direction of the arrow DR1.
- the shape of the information recording medium 1 will be described later with reference to FIGS.
- the information recording medium 1 rotates at a high speed around the rotation center CP.
- the magnetic head 2D is mounted on the tip of the suspension 2C.
- the suspension 2C is provided so as to be rotatable in the direction of the arrow DR2 (tracking direction) with the support shaft 2A as a fulcrum.
- a tracking actuator 2B is attached to the support shaft 2A.
- the magnetic head 2 ⁇ / b> D moves between a retreat position that is disengaged from the information recording medium 1 and a tracking (recording surface) position that floats on the information recording medium 1 in plan view.
- FIG. 2 is a perspective view of the information recording medium glass substrate 1G
- FIG. 3 is a perspective view of the information recording medium 1.
- an information recording medium glass substrate 1G used for the information recording medium 1 (hereinafter referred to as “glass substrate 1G”) has an annular disk shape with a hole 11 formed in the center. ing.
- the glass substrate 1G has an outer peripheral end face 12, an inner peripheral end face 13, a front main surface 14, and a back main surface 15.
- the glass substrate 1G is made of amorphous glass, and has an outer diameter of about 65 mm, an inner diameter of about 20 mm, and a thickness of about 0.8 mm.
- a magnetic thin film layer 23 is formed on the front main surface 14 of the glass substrate 1G.
- the magnetic thin film layer 23 is formed only on the front main surface 14, but it is also possible to provide the magnetic thin film layer 23 on the back main surface 15.
- a conventionally known method can be used as a method for forming the magnetic thin film layer 23 .
- a method of spin-coating a thermosetting resin in which magnetic particles are dispersed a method of forming by sputtering, a method of electroless The method of forming by plating is mentioned.
- the film thickness by spin coating is about 0.3 to 1.2 ⁇ m
- the film thickness by sputtering is about 0.04 to 0.08 ⁇ m
- the film thickness by electroless plating is 0.05 to 0.1 ⁇ m. From the viewpoint of thinning and high density, film formation by sputtering and electroless plating is preferable.
- the magnetic material used for the magnetic thin film layer 23 is not particularly limited, and a conventionally known material can be used. However, in order to obtain a high coercive force, Co having a high crystal anisotropy is basically used to adjust the residual magnetic flux density. Co-based alloys to which Ni and Cr are added are suitable. In recent years, FePt-based materials have been used as magnetic layer materials suitable for heat-assisted recording.
- the surface of the magnetic thin film layer 23 may be thinly coated with a lubricant.
- a lubricant include those obtained by diluting perfluoropolyether (PFPE), which is a liquid lubricant, with a freon-based solvent.
- the underlayer in the information recording medium 1 is selected according to the magnetic film.
- the material for the underlayer include at least one material selected from nonmagnetic metals such as Cr, Mo, Ta, Ti, W, V, B, Al, and Ni.
- the underlayer is not limited to a single layer, and may have a multi-layer structure in which the same or different layers are stacked.
- a multilayer underlayer such as Cr / Cr, Cr / CrMo, Cr / CrV, NiAl / Cr, NiAl / CrMo, or NiAl / CrV may be used.
- Examples of the protective layer for preventing wear and corrosion of the magnetic thin film layer 23 include a Cr layer, a Cr alloy layer, a carbon layer, a hydrogenated carbon layer, a zirconia layer, and a silica layer.
- the protective layer can be formed continuously with an in-line sputtering apparatus, such as an underlayer and a magnetic film.
- the protective layer may be a single layer, or may have a multilayer structure composed of the same or different layers.
- protective layers may be formed on the protective layer or instead of the protective layer.
- colloidal silica fine particles are dispersed and coated on a Cr layer diluted with an alcohol-based solvent, and then fired to form a silicon oxide (SiO2) layer. May be.
- the roll-off value RO is a point B1 on the front main surface 14 where the radial distance from the outer peripheral end face 12 is 1.2 mm and a point B2 where the radial distance from the outer peripheral end face 12 is 0.75 mm.
- An extension line to be connected is defined as a reference position BP, which means a deviation amount between the reference position BP and the selected arbitrary main surface position in the direction in which the rotation axis CL passing through the rotation center CP extends.
- the measurement on the back main surface 15 is the same as the case of the front main surface 14.
- the glass substrate 1G in the present embodiment has a disk shape, and has a radius (R) of about 32.5 mm and a thickness (W) of about 0.8 mm.
- R radius
- W thickness
- an inclined surface 1t having a width (R2) in the radial direction from the outer peripheral end surface 12 of 0.1 mm is provided in a region where the front main surface 14 and the outer peripheral end surface 12 intersect.
- a similar inclined surface 1t is also provided in a region where the back main surface 15 and the outer peripheral end surface 12 intersect.
- R1 is about 32.4 mm.
- the roll-off value RO is mainly formed in the polishing process in the manufacturing process of the glass substrate 1G. If this roll-off value RO becomes too large, when the magnetic head 2D enters from the retracted position toward the tracking (recording surface) position of the information recording medium, the air flow is disturbed, and the magnetic head 2D It becomes a factor that makes levitation unstable (Grain door balanche).
- a flying test of the magnetic head 2D was performed regarding the relationship between the roll-off value RO and the occurrence of turbulence in the air flow.
- the results of the levitation test are shown below as examples.
- Example 1G As the glass substrate 1G, the glass substrate having the size described above was used. 7 types (Example 1, Example 2, Comparative Example 1 to Comparative Example 5) of glass shapes selected from 10 batches processed in a double-side polishing machine in units of 100 batches in the polishing process A substrate was obtained.
- a magnetic thin film layer 23 was formed on the main surface 14 of the glass substrate 1G.
- shape evaluation for measurement (shape evaluation) of the roll-off value RO, OSA6300 manufactured by KLA-Tencor was used.
- recording system a perpendicular magnetic recording system was adopted, and an information recording apparatus 2 having a DFH mechanism as shown in FIG. 1 was used.
- the rotation speed of the information recording medium 1 in the information recording device 2 is 7200 rpm.
- the roll-off value RO was measured for each information recording medium 1. Specifically, the radial direction distance r1 from the outer peripheral end face 12 is 0.55 mm (distance 31.95 mm from the rotation center CP), and the radial distance r2 from the outer peripheral end face 12 is 0.45 mm ( The second radial position P2 at a distance of 32.05 mm from the rotation center CP and the third radial position P3 at a radial distance r3 from the outer peripheral end face 12 of 0.30 mm (a distance of 32.20 mm from the rotation center CP). The roll-off value RO was measured.
- the roll-off value RO at the first radius position P1 was set as the first roll-off value RO1.
- the roll-off value RO at the second radial position P2 was set as the second roll-off value RO2.
- the roll-off value RO at the third radius position P3 was set as the third roll-off value RO3.
- a reference position BP that is an extension line connecting a point at a position 1.2 mm from the outer peripheral end face 12 and a point at a position 0.75 mm from the outer peripheral end face 12 on the front main surface 14. This means that the main surface is located closer to the magnetic head 2D.
- FIG. 5 shows the first roll-off value RO1 at the first radial position P1 and the second roll-off value RO2 at the second radial position P1 of the information recording media 1 of Examples 1 to 6 and Comparative Example 1.
- Each roll-off value is measured in four orthogonal directions passing through the rotation center CP at a radial distance from the outer peripheral end face of the main surface of the information recording medium 1 to be tested to the rotation center CP, and an average value of the four roll-off values RO.
- the roll-off value RO at the radial distance is measured in four orthogonal directions passing through the rotation center CP at a radial distance from the outer peripheral end face of the main surface of the information recording medium 1 to be tested to the rotation center CP, and an average value of the four roll-off values RO.
- a load / unload test (LU) was performed on each information recording medium 1. Repeated 1000 loads / unloads and compared the read output at the first and 1000th head load, and if the output decreased by 20% or more, the head crashed (damaged) and the presence of head crash was confirmed. .
- the magnetic head 2D was run and the flying test of the magnetic head 2D was performed twice at three radial distance positions.
- a first test position GA1 having a radial distance from the outer peripheral end face 12 of 1.3 mm (a distance of 31.2 mm from the rotation center CP), and a radial distance from the outer peripheral end face 12 of 1.1 mm (a distance 31 from the rotation center CP). .4 mm) and a third radial position GA3 having a radial distance from the outer peripheral end face 12 of 0.9 mm (a distance of 31.6 mm from the rotation center CP).
- the result is shown in FIG.
- the flying height from the outermost surface of the magnetic thin film layer 23 of the magnetic head 2D was 5 nm.
- a test was performed using a glide test head equipped with a pico slider in an RQ7800 evaluation apparatus manufactured by Hitachi High-Technologies Corporation.
- Passing the levitation test means a case where the magnetic head 2D passes over the first to third radial positions without causing turbulence of the air flow and without colliding with the protrusions on the surface of the magnetic disk.
- Example 1 the glass substrate used in Example 1 and Example 2 passed the load / unload test (LU), and the evaluation of the flying test was performed at any of the test positions GA1, GA2, and GA3. Is “A”.
- the information recording medium 1 used in Example 3 passed the load / unload test (LU), and the evaluation of the flying test was “A” at the locations of GA1 and GA2, but the evaluation of GA3 was “ C ".
- the information recording medium 1 used in Example 4 passed the load / unload test (LU), the evaluation of GA1 was “A”, the evaluation of GA2 was “B”, and the evaluation of GA3 was “C”.
- the information recording medium 1 used in Example 5 passed the load / unload test (LU), the evaluation of GA1 was “A”, and the evaluation of GA2 and GA3 was “C”.
- the information recording medium 1 used in Example 6 passed the load / unload test (LU), the evaluation of GA1 was “A”, and the evaluation of GA2 and GA3 was “C”.
- the information recording medium 1 used in Comparative Example 1 did not pass the load / unload test (LU).
- a difference (RO1-RO2) between the first roll-off value RO1 and the second roll-off value RO2 is defined as a first roll-off change amount S1
- RO3 be the second roll-off change amount (S2).
- the most preferable range of the first roll-off change amount S1 is 250 ⁇ ⁇ S1 ⁇ 450 ⁇
- the most preferable range of the second roll-off change amount S2 is 9509 ⁇ S2 ⁇ 1870 ⁇ . It is believed that there is.
- the preferable range of the first roll-off change amount S1 is 180 ⁇ ⁇ S1 ⁇ 450 ⁇
- the preferable range of the 2 roll-off change amount S2 is considered to be 810 ⁇ ⁇ S2 ⁇ 2480 ⁇ .
- the preferable range of the first roll-off change amount S1 is 180 ⁇ ⁇ S1 ⁇ 450 ⁇ , from the evaluation results of the first to sixth embodiments.
- the preferable range of the 2 roll-off change amount S2 is considered to be 810 ⁇ ⁇ S2 ⁇ 2480 ⁇ .
- the information recording medium 1 is evaluated by forming the magnetic thin film layer 23 on the glass substrate 1G, but the film of the magnetic thin film layer 23 with respect to the thickness of the glass substrate 1G. Since the thickness is thin, the measurement information and evaluation of the roll-off value RO obtained by each information recording medium 1 can be equated with the measurement information and evaluation of the roll-off value RO of the glass substrate 1G.
- the information recording medium 1 has been described as having a diameter of 65 mm (2.5 inches), but the same applies to other sizes (1.8 inches, 3.5 inches, 5.25 inches). It is possible to obtain the adoption effect.
- the magnetic head when rushing from the retracted position toward the recording surface of the information recording medium, it is possible to suppress the disturbance of the air flow caused by the shape of the area near the outer peripheral end face of the information recording medium.
- 1 information recording medium 1G glass substrate for information recording medium, 1t inclined surface, 2 information recording device, 2A support shaft, 2B tracking actuator, 2C suspension, 2D magnetic head, 11 hole, 12 outer peripheral end surface, 13 inner peripheral end surface, 14 front main surface, 15 back main surface, 23 magnetic thin film layer.
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Abstract
Description
650Å≦第2ロールオフ変化量≦3700Å・・・条件2
他の形態では、上記条件1は、180Å≦第1ロールオフ変化量≦450Åであり、上記条件2は、810Å≦第2ロールオフ変化量≦2480Åである。
図1を参照して、情報記録装置2の概略構成の一例について説明する。図1は、実施の形態における情報記録装置2の概略構成示す図である。
図2および図3を参照して、情報記録媒体用ガラス基板1Gおよび情報記録媒体1の構成について説明する。図2は、情報記録媒体用ガラス基板1Gの斜視図、図3は、情報記録媒体1の斜視図である。
ガラス基板1Gとしては、上述したサイズのガラス基板を用いた。研磨工程にて1バッチ100枚を単位とし,両面研磨装置にて10バッチを加工したものから形状を選別して7種類(実施例1、実施例2、比較例1から比較例5)のガラス基板を得た。
Claims (7)
- 情報記憶装置の情報記録媒体(1)に用いられ、回転中心(CP)を有する円板状の情報記録媒体用ガラス基板であって、
前記磁気薄膜層(23)が形成される主表面(14,15)と、
前記情報記録媒体用ガラス基板(1G)の縁部に位置する外周端面(12)と、を含み、
前記主表面(14,15)の前記外周端面(12)から前記回転中心(CP)に向かう半径方向距離において、
前記主表面(14,15)上における前記外周端面(12)からの前記半径方向距離が1.2mmの位置の点(B1)および前記外周端面(12)からの前記半径方向距離が0.75mmの位置の点(B2)を結ぶ延長線を基準位置(BP)とし、前記回転中心(CP)を通過する回転軸(CL)が延びる方向において、前記基準位置(BP)と選択された任意の前記主表面上の位置とのずれ量をロールオフ値(RO)とした場合に、
前記外周端面(12)からの前記半径方向距離が0.55mmの第1半径位置(P1)における前記ロールオフ値(RO)を第1ロールオフ値(RO1)とし、
前記外周端面(12)からの前記半径方向距離が0.45mmの第2半径位置(P2)における前記ロールオフ値(RO)を第2ロールオフ値(RO2)とし、
前記外周端面(12)からの前記半径方向距離が0.30mmの第3半径位置(P3)における前記ロールオフ値(RO)を第3ロールオフ値(RO3)とし、
前記第1ロールオフ値(RO1)と前記第2ロールオフ値(RO2)との差(RO1-RO2)を第1ロールオフ変化量(S1)とし、
前記第2ロールオフ値(RO2)と前記第3ロールオフ値(RO3)との差(RO2-RO3)を第2ロールオフ変化量(S2)とした場合に、
前記第1ロールオフ変化量(S1)および前記第2ロールオフ変化量(S2)は、下記の条件1および条件2を満足する、情報記録媒体用ガラス基板。
180Å≦第1ロールオフ変化量(S1)≦990Å・・・条件1
650Å≦第2ロールオフ変化量(S2)≦3700Å・・・条件2 - 前記条件1は、180Å≦第1ロールオフ変化量(S1)≦450Åであり、
前記条件2は、810Å≦第2ロールオフ変化量(S2)≦2480Åである、
請求項1に記載の情報記録媒体用ガラス基板。 - 前記条件1は、250Å≦第1ロールオフ変化量(S1)≦450Åであり、
前記条件2は、950Å≦第2ロールオフ変化量(S2)≦1870Åである、
請求項2に記載の情報記録媒体用ガラス基板。 - 前記情報記録媒体用ガラス基板(1G)は、前記主表面(14,15)と前記外周端面(12)とが交わる領域に、前記外周端面(12)からの前記半径方向における幅が0.1mmの傾斜面(1t)を有する、請求項1から3のいずれか記載の情報記録媒体用ガラス基板。
- 前記外周端面(12)から前記回転中心軸(CL)までの前記半径方向距離は、32.5mmである、請求項1から4のいずれかに記載の情報記録媒体用ガラス基板。
- 情報記憶装置に用いられる情報記録媒体(1)であって、
回転中心(CP)を有する円板状の情報記録媒体用ガラス基板(1G)と、
前記情報記録媒体用ガラス基板(1G)の主表面上に設けられる磁気薄膜層(23)と、を備え、
前記情報記録媒体用ガラス基板(1G)は、
前記磁気薄膜層(23)が形成される主表面(14,15)と、
前記情報記録媒体用ガラス基板(1G)の縁部に位置する外周端面(12)と、を含み、
前記主表面(14,15)の前記外周端面(12)から前記回転中心(CP)に向かう半径方向距離において、
前記主表面(14,15)上における前記外周端面(12)からの前記半径方向距離が1.2mmの位置の点(B1)および前記外周端面(12)からの前記半径方向距離が0.75mmの位置の点(B2)を結ぶ延長線を基準位置(BP)とし、前記回転中心(CP)を通過する回転軸(CL)が延びる方向において、前記基準位置(BP)と選択された任意の前記主表面上の位置とのずれ量をロールオフ値(RO)とした場合に、
前記外周端面(12)からの前記半径方向距離が0.55mmの第1半径位置(P1)における前記ロールオフ値(RO)を第1ロールオフ値(RO1)とし、
前記外周端面(12)からの前記半径方向距離が0.45mmの第2半径位置(P2)における前記ロールオフ値(RO)を第2ロールオフ値(RO2)とし、
前記外周端面(12)からの前記半径方向距離が0.30mmの第3半径位置(P3)における前記ロールオフ値(RO)を第3ロールオフ値(RO3)とし、
前記第1ロールオフ値(RO1)と前記第2ロールオフ値(RO2)との差(RO1-RO2)を第1ロールオフ変化量(S1)とし、
前記第2ロールオフ値(RO2)と前記第3ロールオフ値(RO3)との差(RO2-RO3)を第2ロールオフ変化量(S2)とした場合に、
前記第1ロールオフ変化量(S1)および前記第2ロールオフ変化量(S2)は、下記の条件1および条件2を満足する、情報記録媒体。
180Å≦第1ロールオフ変化量(S1)≦990Å・・・条件1
650Å≦第2ロールオフ変化量(S2)≦3700Å・・・条件2 - 前記主表面の片面側での記録密度は、500Gbit/inch2以上である、請求項6に記載の情報記録媒体。
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CN201280048022.4A CN103930947B (zh) | 2011-09-30 | 2012-09-11 | 信息记录介质用玻璃基板以及信息记录介质 |
US14/347,944 US9454984B2 (en) | 2011-09-30 | 2012-09-11 | Information recording medium glass substrate and information recording medium |
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JP2010257562A (ja) * | 2009-03-30 | 2010-11-11 | Hoya Corp | 磁気ディスク用基板及びその製造方法 |
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CN105247615B (zh) * | 2013-06-27 | 2018-06-22 | Hoya株式会社 | 信息记录介质用玻璃基板及磁盘装置 |
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JP5671624B2 (ja) | 2015-02-18 |
CN103930947B (zh) | 2016-12-21 |
JPWO2013047189A1 (ja) | 2015-03-26 |
CN103930947A (zh) | 2014-07-16 |
US20140227561A1 (en) | 2014-08-14 |
MY167649A (en) | 2018-09-21 |
SG11201401063YA (en) | 2014-08-28 |
US9454984B2 (en) | 2016-09-27 |
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