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Patent Agency Ranking
公开(公告)号：US20170140785A1
公开(公告)日：2017-05-18
申请号：US15420502
申请日：2017-01-31
Applicant: HOYA CORPORATION
Inventor： Takeyoshi TAKAHASHI , Masaaki UEDA
CPC classification number: G11B5/7315 , G11B5/73 , G11B5/82
Abstract: A magnetic-disk glass substrate according to the present invention is a doughnut-shaped magnetic-disk glass substrate having a circular hole provided in the center, a pair of main surfaces, and an outer circumferential end surface and an inner circumferential end surface each including a side wall surface and a chamfered surface that is formed between each main surface and the side wall surface. A measurement point is provided on the outer circumferential end surface every 30 degrees in the circumferential direction with reference to a center of the glass substrate, and when a curvature radius of a shape of a portion between the side wall surface and the chamfered surface is determined at each measurement point, the difference in the curvature radius between neighboring measurement points is 0.01 mm or less.
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公开(公告)号：US20170169849A1
公开(公告)日：2017-06-15
申请号：US15442051
申请日：2017-02-24
Applicant: HOYA CORPORATION
Inventor： Masanori TAMAKI , Takeyoshi TAKAHASHI , Masaaki UEDA
CPC classification number: G11B5/82 , G11B5/73 , G11B5/7315 , G11B5/8404
Abstract: 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.
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公开(公告)号：US20190221233A1
公开(公告)日：2019-07-18
申请号：US16368165
申请日：2019-03-28
Applicant: HOYA CORPORATION
Inventor： Takeyoshi TAKAHASHI , Masaaki UEDA
CPC classification number: G11B5/73 , G11B5/7315 , G11B5/82
Abstract: A hard disk drive includes a doughnut-shaped magnetic-disk substrate having a circular hole provided in the center. The doughnut-shaped magnetic-disk substrate includes a pair of main surfaces, and an outer circumferential end surface and an inner circumferential end surface each including a side wall surface and a chamfered surface that is formed between each main surface and the side wall surface. A measurement point is provided on the outer circumferential end surface every 30 degrees in the circumferential direction with reference to a center of the substrate, and when a curvature radius of a shape of a portion between the side wall surface and the chamfered surface is determined at each measurement point, a difference in the curvature radius between neighboring measurement points is 0.01 mm or less.
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4.发明申请公开(公告)号：US20170263278A1
公开(公告)日：2017-09-14
申请号：US15608346
申请日：2017-05-30
Applicant: HOYA CORPORATION
Inventor： Masaaki UEDA
Abstract: A magnetic-disk glass substrate of the present invention includes a pair of main surfaces, a side wall surface, and a chamfered surface between the main surfaces and the side wall surface. Regarding surface properties of at least one of the side wall surface and the chamfered surface of the glass substrate, an arithmetic average roughness (Ra) is 0.015 gm or less, and a bearing factor of a roughness cross-sectional area when a roughness percentage is 60% is 95% or more in a bearing curve of a roughness cross-sectional area.
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公开(公告)号：US20170169848A1
公开(公告)日：2017-06-15
申请号：US15441931
申请日：2017-02-24
Applicant: HOYA CORPORATION
Inventor： Masanori TAMAKI , Takeyoshi TAKAHASHI , Masaaki UEDA
CPC classification number: G11B5/82 , G11B5/7315 , G11B5/8404
Abstract: A magnetic-disk glass substrate has a circular hole at a center, and includes a pair of main surfaces and a side wall surface orthogonal to the main surfaces. A roundness of the circular hole is 1.5 μm or less. A difference between a maximum value and a minimum value of radii of three inscribed circles that are respectively derived from outlines in the circumferential direction at three positions spaced apart by 200 μm in a substrate thickness direction on the side wall surface of the circular hole is 3.5 μm or less.
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