Micro-electromechanical apparatus and method with position sensor compensation
AssigneeTexas Instruments Incorporated
InventorsMark David Heminger, Robert Edward Jansen
Life of this patent
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Abstract
Micro-electromechanical apparatus and method with position sensor compensation to compensate for sensor drift. A preferred embodiment comprises modifying the intensity of a light source used in position detection to maintain a constant sum of the voltages output from photodetectors receiving light from the light source. Preferred embodiments may be implemented in digital signal processor code, or external to the processor in analog circuitry. By adjusting light source intensity, position calculations may be performed without normalization, and thus without a time-consuming division operation.
Claims20
A micro-electromechanical apparatus having position sensor compensation, the apparatus comprising:
- an actuator element;
- a light source for illuminating a portion of the actuator element;
- a plurality of detectors for detecting a light intensity from the light source after reflection from the portion of the actuator element, wherein the light intensity detected at the plurality of detectors is representative of an orientation of the actuator element;
- and
- control circuitry for sending an intensity level signal to the light source and for receiving voltage signals from the plurality of detectors proportional to the intensity of the detected light,
- wherein the control circuitry comprises a summer for adding the voltage signals to generate a voltage sum, and a comparator for comparing the voltage sum to an light intensity setpoint, and wherein the control circuitry adjusts the intensity level signal based on the voltage sum to light intensity setpoint comparison.
A method of compensating for position sensor drift in a micromirror device, the method comprising:
- providing a light intensity level signal to a light source;
- directing light proportional to the light intensity level signal at an underside of a micromirror;
- detecting light reflected from the underside of the micromirror with a plurality of photodetectors;
- generating voltage signals representative of the reflected light detected with the plurality of photodetectors;
- summing the voltage signals to generate a voltage sum;
- comparing the voltage sum to a light intensity setpoint;
- and
- adjusting the light intensity level signal based on the voltage sum to light intensity setpoint comparison.
A micromirror apparatus having position sensor compensation, the apparatus comprising:
- a mirror element;
- a light source for illuminating a portion of an underside of the mirror element;
- a plurality of detectors outputting voltage signals representative of a light intensity detected from the light source after reflection from the underside of the mirror element, wherein the voltage signals are representative of an orientation of the mirror element;
- and
- sensor control circuitry for sending a light intensity signal to the light source and for receiving the voltage signals from the plurality of detectors,
- wherein the control circuitry comprises a summer for adding the voltage signals to generate a voltage sum, and a comparator for comparing the voltage sum to an light intensity setpoint, and wherein the control circuitry adjusts the light intensity signal based on the voltage sum to light intensity setpoint comparison.
Dependencies are inferred from the claim text.