Magnetic fluid seal device
US6769694B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 8, 2003 |
| Grant date | Aug 3, 2004 |
| Priority date | — |
| Expiry date | Apr 8, 2023 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF16J15/43
- WIPO fieldMechanical elements
- WIPO sectorMechanical engineering
Abstract
In a housed state, a magnetic fluid 4 is positioned in a groove 11 and spaced from the outer circumference of a lens barrel 10, so that a fluorochemical surface modification film of the outer circumference of the lens barrel 10 can be prevented from deteriorating at a position to confront the magnetic fluid 4 in the housed state. Therefore, the deterioration of the fluorochemical surface modification film of the outer circumference of the lens barrel 10 does not proceed earlier at a local region, so that the premature wetting of the outer circumference of the lens barrel 10 with the magnetic fluid 4 can be prevented to elongate the lifetime of a light shielding device 1.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.