Projection system using high-frequency drive modulation to reduce perceived speckle
US7972008B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 21, 2008 |
| Grant date | Jul 5, 2011 |
| Priority date | — |
| Expiry date | Mar 31, 2030 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N9/3129
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An image producing system (1400) delivers images (1414) having reduced speckle by employing one or more drive circuits (1404, 1405, 1406) that deliver both a direct current drive signal (205) and an alternating current drive signal (405) to one or more lasers (1401, 1402, 1403). Specifically, an alternating current drive circuit (403) is used in conjunction with a direct current drive circuit (203) to modulate a drive signal. The modulation can be at a frequency of between 400 MHz and 600 MHz. When lasers, such as the red laser (1401) or the blue laser (1403) of a multi-laser system are modulated in such a fashion, their emitted spectral widths (407) greatly expand, thereby reducing speckle in projected images (1414).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.