Rotational angle detector and method
First Claim
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1. A detector for detecting the rotational angle of a rotative member comprising:
- a rotor rotating together with the rotative member;
outer and inner slits located along respective circles, which differ in radius, on the rotor, the center of the circles being the axis of the rotor;
outer and inner sensors located in places corresponding to the outer and inner slits, respectively, wherein the outer and inner sensors detect the presence or absence of each of the slits and generate outer and inner reflective codes, respectively;
a memory for memorizing patterns of data representing variations of reflective codes and corresponding rotational angle data;
a judgment means for judging whether or not a detected reflective code matches a pattern of data in the memory;
a selection means for selecting the rotational angle data corresponding to a pattern that is judged to match a detected reflective code by the judgment means; and
a computing means for computing the rotational angle of the rotor on the basis of the reflective codes generated by the sensors if such reflective codes are not judged to match a pattern of data in the memory by the judgment means.
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Abstract
A rotor is fixed to a steering shaft to rotate with the steering shaft, and outer and inner slits are formed along different circles on the rotor. Outer and inner sensors, which detect the presence or absence of the slits, generate reflective codes and are located next to the rotor. Stored pattern data that matches the reflective code is used to determine the rotational angle. Alternatively, if the pattern data does not match the reflective codes, the rotational angle of the steering shaft is computed on the basis of the reflective codes.
71 Citations
12 Claims
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1. A detector for detecting the rotational angle of a rotative member comprising:
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a rotor rotating together with the rotative member;
outer and inner slits located along respective circles, which differ in radius, on the rotor, the center of the circles being the axis of the rotor;
outer and inner sensors located in places corresponding to the outer and inner slits, respectively, wherein the outer and inner sensors detect the presence or absence of each of the slits and generate outer and inner reflective codes, respectively;
a memory for memorizing patterns of data representing variations of reflective codes and corresponding rotational angle data;
a judgment means for judging whether or not a detected reflective code matches a pattern of data in the memory;
a selection means for selecting the rotational angle data corresponding to a pattern that is judged to match a detected reflective code by the judgment means; and
a computing means for computing the rotational angle of the rotor on the basis of the reflective codes generated by the sensors if such reflective codes are not judged to match a pattern of data in the memory by the judgment means. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for detecting the rotational angle of a rotative member comprising:
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irradiating light on outer and inner slits formed in a rotor that rotates together with the rotative member;
detecting the presence or absence of each slit with outer and inner sensors;
providing reflective codes on the basis of the detection;
comparing the detected reflective codes with stored patterns of data; and
selecting a rotational angle based on the data if the pattern data matches the reflective codes; and
computing a rotational angle of the rotor on the basis of the reflective codes if the reflective codes do not match the pattern data. - View Dependent Claims (8, 9, 10, 11, 12)
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Specification