Rotary encoders
AssigneeSTMicroelectronics (Research & Develoment) Limited
InventorsPatrick Baxter, Jeffrey Raynor
Life of this patent
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Abstract
An optical rotary encoder uses polarization difference imaging techniques to calculate an angle of orientation of a rotatable member. The optical rotary encoder includes a light source, a polarization sensor that has a polarizer and image sensing structure, and a polarizer disk fixed between to the rotatable and interposed between the light source and the polarization sensor.
Claims45
An optical rotary encoder for measuring an angular position of a rotatable member, the optical rotary encoder comprising:
- a light source;
- a polarization sensor comprising a polarizer and an image sensor;
- and
- a polarizer disk fixed to the rotatable member and interposed between said light source and said polarization sensor.
An optical rotary encoder for measuring an angular position of a rotatable member comprising:
- a light source;
- an optical stack comprising
- a polarization sensor, said polarization sensor comprising an integrated polarizer and an image sensor;
- and
- a polarizer disk fixed to the rotatable member and interposed between said light source and the polarization sensor.
An optical rotary encoder for measuring an angular position of a rotatable member comprising:
- a light source;
- a polarization sensor comprising a polarizer and a plurality of image sensors;
- and
- a polarizer disk fixed to the rotatable member and comprising a plurality of tracks of alternating clear and opaque portions, said polarization disk being interposed between said light source and said polarization sensor, each image sensor being associated with one of the tracks on said polarizer disk.
An optical rotary encoder for measuring an angular position of a rotatable member, the optical rotary encoder comprising:
- a light source;
- a polarization sensor comprising a polarizer and an image sensor;
- and
- a polarizer disk fixed to the rotatable member and interposed between said light source and said polarization sensor;
- said polarization sensor using a polarization difference imaging technique.
A method for measuring an angular position of a rotatable member comprising:
- polarizing a light signal through a polarizer disk that rotates with the rotatable member, the polarizer disk having a first direction of polarization;
- further polarizing the light signal in at least one other direction of polarization;
- measuring an intensity of light transmitted after further polarization;
- and
- calculating an angular position based on a comparison of the measured intensity with a known polarization variation.
A method for measuring an angular position of a rotatable member comprising:
- polarizing a light signal transmitted through a polarizer disk rotating with the rotatable member and having at least one first direction of polarization;
- polarizing the transmitted light signal in at least one second direction of polarization;
- measuring an intensity of the transmitted light signal;
- and
- calculating an angular position based on a comparison of the measured intensity of the transmitted light signal with a known polarization variation.
An electronic apparatus comprising:
- a device including a spool fitted with an optical rotary encoder for measuring an angular position of the spool, the encoder comprising
- a light source,
- a polarization sensor comprising a polarizer and an image sensor, and
- a polarizer disk fixed to the rotatable member and interposed between said light source and said polarization sensor.
Dependencies are inferred from the claim text.