Encoder, motor with encoder, and servo system

An encoder, comprising:

• a plurality of slit tracks that respectively comprise a plurality of reflection slits arranged along a measurement direction;
• a point light source configured to emit diffusion light to the plurality of slit tracks;
• two first light-receiving arrays disposed sandwiching the point light source in a width direction substantially orthogonal to the measurement direction;
• two second light-receiving arrays disposed substantially sandwiching the point light source in the measurement direction;
• and
• two third light-receiving arrays that are configured to receive light reflected by the slit track comprising an incremental pattern that differs in pitch from other incremental patterns, and are disposed substantially sandwiching the point light source in the measurement direction between the two first light-receiving arrays.

An encoder, comprising:

• a plurality of slit tracks that respectively comprise a plurality of reflection slits arranged along a measurement direction;
• means for emitting diffusion light to the plurality of slit tracks;
• means for outputting a signal representing a low-accuracy absolute position within one rotation, disposed in duplicate sandwiching the means for emitting the diffusion light in a width direction substantially orthogonal to the measurement direction;
• means for outputting a highly periodical repetition signal, disposed in duplicate sandwiching the means for emitting the diffusion light in the measurement direction;
• and
• means for receiving light reflected by the slit track comprising an incremental pattern that differs in pitch from other incremental patterns, disposed at a position in a direction where the means for outputting a signal representing the low-accuracy absolute position within one rotation is disposed than the means for emitting the diffusion light.