Frequency tunable resonant scanner with auxiliary arms
First Claim
1. A MEMs scanner, comprising:
- a central plate carrying a mirror and having a centerline;
a supporting frame;
at least one torsional member extending between the central plate and the supporting frame; and
a plurality of masses carried by the central plate and distributed radially symmetrically about the scan axis, the plurality of masses having an asymmetric distribution about the mirror centerline.
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Abstract
A MEMs scanning device has a variable resonant frequency. In one embodiment, the MEMs device includes a flexible arm that extends from an oscillatory body. An electrical field applies a force to the flexible arm, thereby bending the flexible arm to change the moment of inertia of the oscillatory body and a secondary mass carried by the flexible arm. The shifted combined center of mass changes the resonant frequency of the MEMs device. In another embodiment, an absorptive material forms a portion of a torsional arm that supports the oscillatory body. The mechanical properties of the absorptive material can be varied by varying the concentration of a gas surrounding the absorptive material. The varied mechanical properties change the resonant frequency of the scanning device. A display apparatus includes the scanning device and the scanning device scans about two or more axes, typically in a raster pattern. Various approaches to controlling the frequency responses of the scanning device are described, including active control of MEMs scanners and passive frequency tuning.
70 Citations
9 Claims
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1. A MEMs scanner, comprising:
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a central plate carrying a mirror and having a centerline;
a supporting frame;
at least one torsional member extending between the central plate and the supporting frame; and
a plurality of masses carried by the central plate and distributed radially symmetrically about the scan axis, the plurality of masses having an asymmetric distribution about the mirror centerline. - View Dependent Claims (2, 3, 4)
a substrate;
at least one torsional member extending between the supporting frame and the substrate, the torsional member defining a rotation axis substantially parallel to the centerline.
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5. An optical scanning system comprising:
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a light source, operative to emit a beam of light;
a MEMs structure including;
a central plate carrying a mirror and positioned to intercept the beam of light;
an actuator positioned to provide a motive force to the central plate a supporting frame carrying the central plate, wherein the central plate is responsive to the motive force to rotate about a primary pivot axis relative to the supporting frame at a primary rotation frequency, the central plate further including an asymmetric mass distribution selected to produce rotation about a second axis orthogonal to the pivot axis in response to rotation of the central plate about the primary pivot axis. - View Dependent Claims (6)
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7. A method of scanning a light beam through a raster pattern having a line rate and a refresh rate, comprising the steps of:
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directing the light beam toward a mirror having a primary body and at least one mass carried by the primary body;
actuating the primary body with a first motive force aligned to produce rotation of the primary body about a primary pivot axis at an integral multiple of the line rate, wherein the at least one mass acts on the primary body to produce a rotational component about a second axis orthogonal to the primary pivot axis;
rotating the mirror with a second motive force about the second axis at the refresh rate. - View Dependent Claims (8, 9)
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Specification