Evaluation method of magnetic disk, manufacturing method of magnetic disk, and magnetic disk

{
  "publication_number": "US2012077060A1",
  "country": "US",
  "kind": "A1",
  "title": "Evaluation method of magnetic disk, manufacturing method of magnetic disk, and magnetic disk",
  "abstract": "An evaluation method that can easily evaluate properties of a carbon protective film and a lubricant on a magnetic-disk surface or particularly, an evaluation method of a magnetic disk in which the properties of the magnetic-disk surface can be evaluated accurately so that a strict demand for interactions between the magnetic-disk surface and a head can be met is provided. In a state in which an element portion of the magnetic head provided with the head element portion that projects by thermal expansion is projected, after being brought into contact with a predetermined radial position on the surface of the rotating magnetic disk, the head is further made to perform seeking in a state in which the element portion is projected by a specified amount, whereby the properties of the carbon film or the lubricant formed on the magnetic-disk surface is evaluated.",
  "claims": [
    "1. An evaluation method of a magnetic disk, characterized in that in a state in which an element portion of a magnetic head provided with the head element portion that projects by thermal expansion is projected, after being brought into contact with a predetermined radial position on the surface of a rotating magnetic disk, the magnetic head is further made to perform seeking in a state in which said element portion is projected by a specified amount, whereby properties of a carbon film or a lubricant formed on the surface of the magnetic disk are evaluated. 2. The evaluation method of a magnetic disk according to claim 1, wherein the projecting amount of said head element portion at measurement is within a range of 0.1 to 10 nm. 3. The evaluation method of a magnetic disk according to claim 1 or 2, wherein a contact radius of said head element portion at measurement is a region excluding 1 mm and inside from an inner peripheral edge portion and 0.1 mm and outside from an outer edge portion of the magnetic disk. 4. The evaluation method of a magnetic disk according to any one of claims 1 to 3, wherein contact time of said head element portion at measurement is 30 seconds or more. 5. The evaluation method of a magnetic disk according to any one of claims 1 to 4, wherein a seek speed at measurement is within a range from 0.1 to 3.0 m/s. 6. The evaluation method of a magnetic disk according to any one of claims 1 to 5, wherein a magnetic disk rotation speed at measurement is within a range of 100 to 20000 rpm. 7. A manufacturing method of a magnetic disk, comprising: a process in which on the basis of an evaluation result by the evaluation method of a magnetic disk according to any one of claims 1 to 6, a manufacturing condition of a lubrication layer is determined and a lubrication layer is formed on the surface of the magnetic disk in accordance with the determined manufacturing condition. 8. The manufacturing method of a magnetic disk, comprising: a process in which on the basis of an evaluation result by the evaluation method of a magnetic disk described in any one of claims 1 to 6, a manufacturing condition of a carbon protective layer is determined and the carbon protective layer is formed on the surface of the magnetic disk in accordance with the determined manufacturing condition. 9. A magnetic disk determined as acceptable by the evaluation method of a magnetic disk according to any one of claims 1 to 6."
  ],
  "cpc": [
    "G11B 5/455",
    "G11B 5/3136",
    "G11B 5/607",
    "G11B 5/8408",
    "Y10T 29/49764"
  ],
  "assignees": [
    "OZAWA TSUYOSHI",
    "WD MEDIA SINGAPORE PTE LTD"
  ],
  "filing_date": "2011-03-29",
  "publication_date": "2012-03-29",
  "priority_date": "2010-03-29",
  "application_number": "US-201113074369-A",
  "family_id": "44941198",
  "citations": [
    "US5309301A",
    "US5541789A",
    "US6356405B1",
    "US6760175B2",
    "US6914739B2",
    "US7573682B2"
  ]
}