Method and apparatus for controlling the focus of a read/write head for an optical scanner
US6584052B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 2, 1998 |
| Grant date | Jun 24, 2003 |
| Priority date | — |
| Expiry date | Jun 2, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/0281
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A controller for a scanning head images light from the scanning head onto a target surface for reading and writing data. Light returned from the target surface is received by the same aperture. Light may be conducted from the aperture, for example, by a light waveguide leading to a detector. The focus control of the imaging optics is controlled responsively to the light returned through the aperture. When this returned light is at a maximum, the focusing optics are in focus. A focus controller may be programmed to dither (intentionally vary) the configuration of the optics to determine the focus optimization direction (gradient). In an embodiment with multiple apertures, each employed to scan a respective area of the target surface (in parallel), the light from adjacent apertures is effectively rejected each other aperture thereby eliminating crosstalk.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.