Photoelectric encoder

A photoelectric encoder comprising:

• a scale that has a diffraction grating formed at a predetermined pitch in a measurement axis direction;
• a detection head that irradiates the scale with light and receives light reflected by the scale;
• a plurality of fibers through which the light that is to be irradiated on the scale and the light reflected by the scale propagates;
• a first cable that has an inner space in which the plurality of fibers is partially disposed;
• a second cable that has an inner space in which the plurality of fibers is partially disposed;
• and
• a frame unit inside which a light source and a light-sensitive element are provided, the light source supplying light to the plurality of fibers or at least one of the plurality of fibers, the light-sensitive element receiving the reflected light propagating through the plurality of fibers or the others of the plurality of fibers and converting the received light into an electric signal,
• wherein the first cable, the second cable, and the frame unit are disposed in this order in a direction of propagation of the light reflected by the scale through the plurality of fibers or the others of the plurality of fibers,
• the plurality of fibers is partially disposed in the inner space of the first cable in such a manner that the positions of the fibers are fixed relative to one another in a direction orthogonal to a direction of length of the fibers, and
• the plurality of fibers is partially disposed in the inner space of the second cable in such a manner that the positions of the fibers are variable relative to one another in the direction orthogonal to the direction of the length of the fibers.