Showing papers by "James M. Florence published in 1998"

Improvements in or relating to spatial light modulators

Abstract: A DMD spatial light modulator (20) having an improved reset waveform (80) that improves the electrostatic control over the DMD mirrors (30) during switching states (T3). An intermediate bias level is provided to the yoke (32) and mirror (30) during the mirror reset cycle (T3) which is sufficient to maintain a voltage differential between the mirror/yoke and the address electrodes (26,28,50,52) to dynamically park the mirror during a same-state transition, but which voltage differential is insufficient to overcome the hinge restoration forces during an opposite-state transition such that the mirror releases toward the neutral position and can be captured in the other state upon reapplication of the bias voltage. The transition bias level is maintained for a sufficient time period (T3) to allow the mirror/yoke to release from the landing pads (82) a sufficient distance toward the neutral position. The operating reliability of the device is improved by preventing incident light during same-state mirror transitions from escaping into the display aperture, without impeding the crossover of the mirror during opposite-state mirror transitions. Greater mirror-to-mirror variations can be tolerated without falling outside the mirror arrays acceptable timing operating parameters.

Spatial optical modulator having improved contrast ratio

Abstract: PROBLEM TO BE SOLVED: To reduce the diffraction of incident light on a projection optical system and to improve a contrast ratio by turning a support edge to be in parallel with a mirror edge and specifying an incident angle on both the support edge and the mirror edge. SOLUTION: This spatial optical modulator 70 is improved by providing each mirror 72 with a mirror support 74 fixing the support edge 76 turned at 45 deg. to all the incident beams of light generated by a light source 80. The edge 76 is parallel with the corresponding mirror edge T8 of the mirror 72 and the edge 78 is turned at 45 deg. to the incident beam of the light generated by the light source 80. The direction of the edge 76 to the incident light beam minimizes the diffraction of the light scattered to a dark field projection system optical system when a mirror surface is turned to an off-state. By turning the edge 76 to be extended at 45 deg. to the incident beam of the light, the diffraction of the light is minimized and the formation of a diffrated light spot to the projection optical system is reduced and the diffraction of the light to the projection optical system from a corner is reduced.