Aluminum head drum with a protective layer which smoothly and continuously varies in hardness for use in a videocassette recorder
US5883769A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 30, 1997 |
| Grant date | Mar 16, 1999 |
| Priority date | — |
| Expiry date | Jun 30, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B15/62
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An aluminum head drum for use in a video cassette recorder is coated with a protective layer comprising diamond-like carbon. The protective layer of diamond-like carbon is obtained using a plasma-enhanced chemical vapor deposition method and has a thickness ranging from 0.3 .mu.m to 2.0 .mu.m. The protective layer has a varying mechanical hardness, wherein the mechanical hardness has a maximum value at a region of the protective layer coming in contact with the aluminum head drum, decreases smoothly and continuously and reaches an minimum value at a region of the protective layer coming in contact with atmosphere. Micro-Vicker's hardness of the region of the protective layers coming in contact with a video tape is 1.5-2.0 times that of the magnetic substance constituting the video tape.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.