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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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Patent Agency Ranking
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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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：US20160005431A1
公开(公告)日：2016-01-07
申请号：US14770025
申请日：2014-02-28
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.
Abstract translation: 磁盘玻璃基板具有圆形中心孔，一对主表面和边缘表面。 边缘表面具有插入在侧壁表面和主表面之间的侧壁表面和倒角表面，并且外周侧上的边缘表面的圆度为1.5μm以下。 此外，分别从外周侧的侧壁面上的基板厚度方向上隔开200μm的两个位置以及中心B和 分别从基板厚度方向的外周侧的两个倒角面的相应一个中分别导出，以使得A和B之间的距离之和以及A和C之间的总和为1μm以下。
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公开(公告)号：US20150371673A1
公开(公告)日：2015-12-24
申请号：US14767515
申请日：2014-02-24
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.
Abstract translation: 磁盘玻璃基板在中心具有圆形孔，并且包括一对主表面和与主表面正交的侧壁表面。 圆孔的圆度为1.5μm以下。 圆孔的侧壁面的基板厚度方向间隔开200μm的三个位置的圆周方向的轮廓的最大值和最小值的最小值与最小值之间的差为3.5 μm以下。
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