Frequency tunable resonant scanner
First Claim
1. A microelectromechanical resonant device, comprising:
- a base;
a movable body coupled to the base for resonant motion relative to the base about a pivot axis;
an enclosure surrounding the movable body and at least a portion of the base;
a flexible member extending between the movable body and the base, the flexible member including a gas absorbing material, the gas absorbing material having material properties responsive to a partial pressure of a selected gas within the enclosure wherein the responsive material properties define a resonant frequency of the resonant motion; and
an electrically activated pressure controller, coupled to the enclosure and responsive to an electrical signal to increase or decrease the partial pressure of the gas.
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Accused Products
Abstract
A display apparatus includes a scanning assembly that scans about two or more axes, typically in a raster pattern. A plurality of light sources emit light from spaced apart locations toward the scanning assembly such that the scanning assembly simultaneously scans more than one of the beams. The scanning assembly is a resonant scanning assembly with a variable resonant frequency. The resonant frequency of the scanning assembly can be actively controlled by controlling partial pressure of fluids in a package containing the scanning assembly. In one embodiment, the increased partial pressure increases the mass of a scanning mirror, thereby changing the resonant frequency. In another embodiment, a gas absorbing material is coupled to a support arm that carries a scanning mirror. As the gas absorbing material absorbs gas, its physical properties change, thereby shifting the resonant frequency of the scanning assembly. Monitoring the resonant frequency relative to a desired frequency provides in error signal that can be used to frequency lock the resonant scanning assembly to an input signal.
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Citations
15 Claims
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1. A microelectromechanical resonant device, comprising:
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a base;
a movable body coupled to the base for resonant motion relative to the base about a pivot axis;
an enclosure surrounding the movable body and at least a portion of the base;
a flexible member extending between the movable body and the base, the flexible member including a gas absorbing material, the gas absorbing material having material properties responsive to a partial pressure of a selected gas within the enclosure wherein the responsive material properties define a resonant frequency of the resonant motion; and
an electrically activated pressure controller, coupled to the enclosure and responsive to an electrical signal to increase or decrease the partial pressure of the gas. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An optical scanner comprising:
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an oscillatory body;
a body support coupled to the oscillatory body and configured to permit the oscillatory body to move about a pivot axis;
a container containing the oscillatory body, the body support, and a selected fluid;
a movable mass carried by the oscillatory body and offset from the pivot axis, the movable mass being of a type that absorbs the selected fluid; and
a source of the selected fluid coupled to or within the container, the source of the selected fluid being responsive to an electrical signal to increase or decrease the concentration of the selected fluid within the container. - View Dependent Claims (8, 9)
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10. A resonant scanning apparatus having a controllable resonant frequency, comprising:
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a first body;
a second body coupled to the first body, the first and second bodies being sized and configured for relative motion at a first resonant frequency; and
a variable mass coupled to one of the first and second bodies, the variable mass being positioned to produce a force on the first or second body, wherein the first and second bodies are responsive to the force to move at a second resonant frequency different from the first resonant frequency, the variable mass being responsive to an input to increase or decrease in mass while the first and second bodies are in relative motion. - View Dependent Claims (11, 12, 13, 14, 15)
an electrical signal source electrically coupled to the variable mass in response to a control signal.
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15. The resonant scanning apparatus of claim 14 further comprising a motion sensor coupled to detect relative motion of the first and second bodies, the motion sensor being operative to produce the control signal in response to the detected relative motion.
Specification