Grid-actuated charge controlled mirror and method of addressing the same
First Claim
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1. A light modulator, comprising:
- an array of electrostatically-actuable micromirrors;
a collector grid that is biased at a grid potential;
an anode electrode spaced apart from said micromirror array opposite said collector grid; and
a source that emits primary electrons which accelerate towards the anode electrode, pass through said collector grid and strike the micromirrors thereby ejecting secondary electrons and depositing a negative charge pattern on said micromirrors,said collector grid collecting the ejected secondary electrons and producing attractive electrostatic forces that deflect said micromirrors toward said collector grid in accordance with the difference between said grid potential and the respective micromirror potentials induced by said negative charge pattern.
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Abstract
A micromirror light valve target configuration that overcomes the problems of limited deflection range, electrostatic and resolution by forming the secondary electron collector grid of a fine conductive mesh and placing it in close proximity to the micromirror array. The source, preferably a fixed beam array, addresses the micromirror array such that it exhibits a secondary emission coefficient less than one to write a negative charge pattern onto the mirrors so that they are attracted to the collector grid. If the anode is also in close proximity to the array, the mirrors can be addressed so that they deflect up toward the grid and down toward the anode thereby increasing the deflection range.
61 Citations
21 Claims
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1. A light modulator, comprising:
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an array of electrostatically-actuable micromirrors; a collector grid that is biased at a grid potential; an anode electrode spaced apart from said micromirror array opposite said collector grid; and a source that emits primary electrons which accelerate towards the anode electrode, pass through said collector grid and strike the micromirrors thereby ejecting secondary electrons and depositing a negative charge pattern on said micromirrors, said collector grid collecting the ejected secondary electrons and producing attractive electrostatic forces that deflect said micromirrors toward said collector grid in accordance with the difference between said grid potential and the respective micromirror potentials induced by said negative charge pattern. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A light modulator, comprising:
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an anode that is held at an anode potential; a collector grid that is spaced apart from said anode, said collector grid being biased at a grid potential above said anode potential to establish a uniform electric field; an array of electrostatically-actuable micromirrors between said collector grid and said anode and in said uniform electric field, said micromirrors assuming a floating potential at which the opposing attractive forces to said collector grid and said anode cancel; an array of control pads on said respective micromirrors that exhibit an electron affinity opposite that of said micromirrors, said control pads only partially covering said micromirrors so that each said micromirror has a first portion that has a secondary emission coefficient less than one and a second portion that has a secondary emission coefficient greater than one; and an array of fixed sources that emit primary electrons which are accelerated toward said anode, pass through said collector grid and strike the micromirrors'"'"' first and second portions thereby ejecting secondary electrons into said uniform electric field that are collected by said collector grid and leaving a charge pattern on said micromirrors that modulates the micromirrors'"'"' floating potentials, said collector grid comprising a fine conductive mesh that is positioned close enough to said array of micromirrors that the change in the micromirrors'"'"' floating potentials produces sufficient imbalances in the opposing attractive forces to deflect said micromirrors outward toward said collector grid in accordance with said charge pattern. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A light modulator, comprising:
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a transparent substrate; an anode electrode on said substrate that is held at an anode potential; an array of electrostatically-actuable micromirrors on said substrate; a collector grid that is spaced apart from said micromirrors opposite said anode electrode, said collector grid being held at a grid potential above said anode potential to establish a uniform electric around the array of micromirrors, said micromirrors stabilizing at a floating potential at which the opposing attractive forces to said collector grid and said anode electrode cancel; and an array of sources that emit primary electrons which pass through said collector grid and strike the micromirrors thereby ejecting secondary electrons into said uniform electric field that are collected by said collector grid and leaving a charge pattern on said micromirrors that modulates their floating potentials, said collector grid and said anode layer being positioned close enough to said array of micromirrors that the modulation of the micromirrors'"'"' floating potentials produces sufficient imbalances in the opposing attractive forces to selectively deflect said micromirrors toward said collector grid and said anode layer when said charge pattern is negative and positive, respectively. - View Dependent Claims (15, 16, 17, 18)
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19. A method of addressing a micromirror light modulator having an array of micromirrors positioned between an anode electrode and a collector grid, which is biased at a grid potential above the anode potential, comprising:
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directing primary electrons onto said micromirrors to eject secondary electrons and write a negative charge pattern onto said micromirrors; collecting the secondary electrons to hold the negative charge pattern; and attracting said collector grid in accordance with said negative charge pattern. - View Dependent Claims (20, 21)
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Specification