Servomotor and encoder

A servomotor comprising:

• a motor including a rotational shaft;
• and
• an encoder that generates multiple rotation data obtained by counting rotations of the rotational shaft using a rotation signal that indicates one rotation of the rotational shaft, one-rotation data calculated using an angle signal that indicates a rotational angle of the rotational shaft and indicating a rotational angle within one rotation, and accumulated multiple rotation data obtained by accumulating the rotational angles using the angle signal and by counting the rotations of the rotational shaft whenever the rotational shaft makes one rotation, and that transmits either the multiple rotation data or the accumulated multiple rotation data and the one-rotation data to a motor control device, wherein
• the encoder includes
• a rotation detection unit that detects a rotational position of the rotational shaft,
• a multiple rotation counter that generates the multiple rotation data using the rotation signal generated based on the rotational position,
• a first cumulative-number calculation unit that calculates first accumulated multiple rotation data using the angle signal generated based on the rotational position,
• a second cumulative-number calculation unit that calculates second accumulated multiple rotation data using the angle signal generated based on the rotational position, and
• a comparative diagnosis unit that performs a comparison to determine whether at least three values including at least one value relating to number of rotations and generated using the rotation signal and at least two values relating to number of rotations and calculated using the angle signal are a same value by performing a comparison to determine whether the multiple rotation data, the first accumulated multiple rotation data, and the second accumulated multiple rotation data are a same value, and that diagnoses whether the encoder has a fault based on a comparison result.

An encoder that generates multiple rotation data obtained by counting rotations of a rotational shaft of a motor that includes the rotational shaft using a rotation signal that indicates one rotation of the rotational shaft, one-rotation data calculated using an angle signal that indicates a rotational angle of the rotational shaft and indicating a rotational angle within one rotation, and accumulated multiple rotation data obtained by accumulating the rotational angles using the angle signal and counting the rotations of the rotational shaft whenever the rotational shaft makes one rotation, and transmits either the multiple rotation data or the accumulated multiple rotation data and the one-rotation data to a motor control device, the encoder comprising:

• a rotation detection unit that detects a rotational position of the rotational shaft;
• a first multiple rotation counter that generates first multiple rotation data using the rotation signal generated based on the rotational position;
• a second multiple rotation counter that generates second multiple rotation data using the rotation signal generated based on the rotational position;
• a first cumulative-number calculation unit that calculates first accumulated multiple rotation data using the angle signal generated based on the rotational position;
• a second cumulative-number calculation unit that calculates second accumulated multiple rotation data using the angle signal generated based on the rotational position;
• and
• a first comparative diagnosis unit that performs a comparison to determine whether at least four values including at least two values relating to number of rotations and generated using the rotation signal and at least two values relating to number of rotations and calculated using the angle signal are a same value by performing a comparison to determine whether the first multiple rotation data, the second multiple rotation data, the first accumulated multiple rotation data, and the second accumulated multiple rotation data are a same value, and that diagnoses whether the encoder has a fault based on a comparison result.