Projection system and mirror elements for improved contrast ratio in spatial light modulators
US6523961B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 7, 2000 |
| Grant date | Feb 25, 2003 |
| Priority date | — |
| Expiry date | Feb 10, 2021 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB82Y30/00
- WIPO fieldMicro-structural and nano-technology
- WIPO sectorChemistry
Abstract
In order to minimize light diffraction along the direction of switching and more particularly light diffraction into the acceptance cone of the projection optics, in the present invention, mirrors are provided which are not rectangular. Also, in order to minimize the cost of the illumination optics and the size of the display unit of the present invention, the light source is placed orthogonal to the rows (or columns) of the array, and/or the light source is placed orthogonal to a side of the frame defining the active area of the array. The incident light beam, though orthogonal to the sides of the active area, are not however, orthogonal to any substantial portion of sides of the individual mirrors in the array. Orthogonal sides cause incident light to diffract along the direction of mirror switching, and result in light ‘leakage’ into the on-state even if the mirror is in the off-state. This light diffraction decreases the contrast ratio of the mirror. The mirrors of the present invention result in an improved contrast ratio, and the arrangement of the light source to mirror array in the present invention results in a more compact system.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.