Hidden hinge digital micromirror device with improved manufacturing yield and improved contrast ratio
AssigneeTexas Instruments Incorporated
InventorsRobert E. Meier, James D. Huffman
Life of this patent
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Abstract
An improved DMD type spatial light modulator having an array of pixels (18). The pixels (18) are of the “hidden hinge” design, each pixel having a mirror (30) supported over a hinged yoke (32). Addressing electrodes (26, 28) on an underlying metallization layer and addressing electrodes (50, 52) at the yoke level provide electrostatic forces that cause the mirrors to tilt and then to return to their flat state. The pixels (18) are designed to provide increased clearance between the leading edge of the yoke (32) and the underlying metallization layer when the mirrors (30) are tilted. Various features of the improved pixel (18) also improve the contrast ratio of images generated by the DMD.
Claims16
A spatial light modulator fabricated on a substrate, comprising:
- addressing circuitry comprising a first portion proximate the substrate and a second portion elevated above the substrate;
- a yoke supported over the addressing circuitry first portion;
- a pair of springtips at each leading edge of the yoke, the springtips operable to land on the addressing circuitry first portion;
- at least one hinge connected to the yoke and supporting the yoke, the hinge permitting tilting of the yoke in response to electrostatic addressing;
- and
- a mirror elevated above and supported by the yoke, the mirror positioned over the elevated addressing circuitry second portion;
- wherein the spacing between the springtips of each springtip pair and the height of the yoke over the addressing circuitry first portion, are increased for optimal performance;
- wherein the optimal performance provides increased clearance between the addressing circuitry first portion and the leading edge of the yoke without significant comprise to electrostatic performance.
A method of constructing an array of mirrors, such that each mirror is individually rotateable into at least two states, comprising the steps of:
- constructing a metallization layer for electrostatically addressing the mirrors of the array;
- constructing a yoke layer in a plane separate from the plane of the metallization layer, the yoke layer comprising at least a yoke for supporting each mirror, and a hinge for supporting the yoke over the metallization layer, wherein the hinge permits the yoke to tilt in response to electrostatic addressing, and further comprising a pair of springtips at each leading edge of the yoke, the springtips operable to land on the metallization layer when the mirror is tilted;
- and
- constructing a mirror layer in which the mirrors are fabricated;
- increasing the spacing between the springtips of each springtip pair and the height of the yoke for optimal performance;
- wherein the optimal performance provides increased clearance between the addressing circuitry first portion and the leading edge of the yoke without significant comprise to electrostatic performance.
Dependencies are inferred from the claim text.