Rotary position detector and associated methods
OwnerWilliam R. Benner, Jr.inventor
Life of this patent
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Abstract
A rotary position detector includes a housing having an inner space having a reflective element. A light source emits light rays upwardly. A base supports a light detector assembly having a first number of toroidal-sector-shaped light sensors disposed in pairs about a motor shaft axis, one “A” detector element and one “B” detector element alternately disposed. A light blocker positioned between the light source and the light sensors rotates with the shaft. The light blocker includes a second number of opaque, equal-surface-area elements arrayed about the axis, the second number equal to one-half the first number. A circuit measures a signal from the “A” and “B” detectors relating to an amount of light falling thereon, a difference related to an angular position of the motor shaft.
Claims28
A rotary position detector comprising:
- a housing having an inner space;
- a shaft extending into the housing inner space, the shaft rotatable about an axis thereof;
- a light source positioned to emit light rays into the housing inner space;
- a light detector positioned within the housing inner space in a spaced relation to the light source, the light detector comprising a first number of segmented light sensors disposed in pairs about the axis, each pair comprising one “A” detector element and one “B” detector element, the pairs disposed so that each “A” detector element is circumferentially positioned between two “B” detector elements and each “B” detector element is positioned between two “A” detector elements;
- a light blocker positioned between the light detector and the light source, the light blocker comprising a second number of opaque, substantially equal-surface-area elements rotatable with the shaft, the second number equal to one-half of the first number, wherein a radial extent of the light blocker elements is less than a radial extent if the light sensors;
- and
- a signal connection to the light detector for measuring an amount of light impinging on the segmented light sensors to thus measure a rotary position of the shaft.
A method of detecting a rotary position of a shaft comprising, the method comprising:
- transmitting light into an inner space of a housing having a shaft extending therethrough and rotatable about an axis thereof;
- detecting at least some of the light with a light detector positioned within the housing inner space, wherein the light detector comprises a first number of segmented light sensors disposed in pairs about the axis of the shaft, each pair comprising one “A” detector element and one “B” detector element, the pairs disposed so that each “A” detector is circumferentially positioned between two “B” detectors and each “B” detector is positioned between two “A” detectors;
- blocking a portion of the light with a light blocker positioned within the housing inner space and rotatable with the shaft, the light blocker comprising a second number of opaque, substantially equal-surface-area elements arrayed about the axis, the second number equal to one-half of the first number, the blocked light portion thereby unable to reach the light sensors, wherein an outer extent of the light blocker is no greater than an outer extent of the light sensors;
- and
- processing a signal received from the “A” detectors and the “B” detectors relating to an amount of light impinging thereon, wherein a difference between the “A” detector signal and the “B” detector signal is related to a rotary position of the shaft.
Dependencies are inferred from the claim text.