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US 2017/0256278 A1Published application
Magnetic-disk substrate having a small waviness, for use as a magnetic disk, and a magnetic-disk drive device for use with the magnetic disk
AssigneeHoya Corporation
InventorsTakashi MAEDA, Takumi KUHARA
Life of this patent
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Abstract
When waviness having a wavelength component of 10 to 500 μm in the circumferential direction of a main surface of a disk-shaped substrate is acquired and slopes are acquired from the waviness at an interval of 50 to 100 μm, the substrate being used in a magnetic disk on which recording or reading is performed using a DFH head, an average value of absolute values of the slopes is 0.45×10−4 or less. This magnetic-disk substrate is used in a magnetic disk and a magnetic-disk drive device.
Claims19
A magnetic-disk substrate comprising:
- at least one main surface, configured such that when waviness having a wavelength component of 10 μm to 500 μm on the main surface is acquired in a circumferential direction of the main surface and slopes are acquired from the waviness at an interval of 50 μm to 100 μm, an average value of absolute values of the slopes is 0.45×10−4 or less, an arithmetic average roughness Ra of the main surface being 0.3 nm or less.
A magnetic-disk substrate comprising:
- at least one main surface, configured such that when waviness having a wavelength component of 10 μm to 500 μm for one turn at a position located 20.86 mm away from a center of the magnetic-disk glass substrate on the main surface is acquired in a circumferential direction of the main surface and slopes are acquired from the waviness at an interval of 50 μm to 100 μm, an average value of absolute values of the slopes is 0.45×10−4 or less.
Dependencies are inferred from the claim text.