Temperature compensation for strain sensor
AssigneeMicrosoft Technology Licensing, LLC
InventorsXiao Chuan ONG, Wyatt Owen DAVIS
Life of this patent
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Abstract
A strain sensor that has an associated temperature compensation circuit. The strain sensor is temperature-compensated as it has a temperature compensation circuit that, when powered, applies an applied voltage across the applied voltage terminals of the strain sensor that has a compensating temperature dependency. That is, the applied voltage has a temperature dependency of one polarity that is opposite a temperature dependency of the strain sensor. Because of this temperature compensation, the signal representing strain has a more stable scale factor between the endured strain and the signal representing the strain. Thus, the accuracy of the strain sensor is improved.
Claims20
A temperature-compensated strain sensor comprising:
- a strain sensor comprising applied voltage terminals, and strain measurement terminals, the strain sensor and configured such that when an applied voltage is applied across the applied voltage terminals, the strain sensor generates a signal on the strain measurement terminal that depends on strain endured by the strain sensor, the strain sensor also have a temperature dependency for a constant applied voltage applied across the applied voltage terminals;
- and
- a temperature compensation circuit configured to, when powered, apply the applied voltage across the applied voltage terminals of the strain sensor such that the applied voltage has a temperature dependency of one polarity that is opposite a temperature dependency of the strain sensor.
The temperature-compensated strain sensor in accordance with Claim the first component and the second component having temperature dependencies that are opposite in polarity.
The temperature-compensated strain sensor in accordance with Claim the second component comprising a diode, and having adjustable temperature dependency by adjusting an amount of current passing through the diode.
A micro-mirror assembly comprising:
- a mirror situated on a tortional elongated axial structure that is elongated along a rotational axis of the mirror;
- a temperature-compensated strain sensor situated with respect to the tortional elongated axial structure so as to experience strain in approximate proportion to a rotation of the mirror about the rotational axis, the strain sensor comprising:
- a Wheatstone bridge comprising a plurality of piezoresistive elements, two opposite nodes of the bridge comprising applied voltage terminals, and other two opposite nodes of the bridge comprising measurement terminals, the bridge configured such that when an applied voltage is applied across the applied voltage terminals, the bridge generates a signal on the strain measurement terminal that depends on strain endured by the bridge, the bridge also have a temperature dependency for a constant applied voltage applied across the applied voltage terminals;
- and
- a temperature compensation circuit configured to, when powered, apply the applied voltage across the applied voltage terminals of the strain sensor such that the applied voltage has a temperature dependency of one polarity that is opposite a temperature dependency of the strain sensor, the temperature dependency of the bridge being negative, the temperature compensation circuit configured such that, when powered, the temperature dependency of the applied voltage is positive.
A micro-mirror assembly comprising:
- a mirror situated on a tortional elongated axial structure that is elongated along a rotational axis of the mirror;
- a temperature-compensated strain sensor situated with respect to the tortional elongated axial structure so as to experience strain in approximate proportion to a rotation of the mirror about the rotational axis, the strain sensor comprising:
- a Wheatstone bridge comprising a plurality of piezoresistive elements, two opposite nodes of the bridge comprising applied voltage terminals, and other two opposite nodes of the bridge comprising measurement terminals, the bridge configured such that when an applied voltage is applied across the applied voltage terminals, the bridge generates a signal on the strain measurement terminal that depends on strain endured by the bridge, the bridge also have a temperature dependency for a constant applied voltage applied across the applied voltage terminals;
- and
- a temperature compensation circuit configured to, when powered, apply the applied voltage across the applied voltage terminals of the strain sensor such that the applied voltage has a temperature dependency of one polarity that is opposite a temperature dependency of the strain sensor, wherein the temperature dependency of the applied voltage offsets from 75 to 125 percent of the temperature dependency of the strain sensor for temperatures between minus 20 Celsius and positive 60 degrees Celsius.
Dependencies are inferred from the claim text.