Patent ID: 8395108
Filing Date: 2013-03-12
Classification: G01D,G02B

Abstract:
1. 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, the detection head comprising a cylindrical ferrule; 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; a coupling part disposed between the detection head and the first cable and connecting the detection head and the first cable; 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, 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, an inside diameter of the second cable is larger than an inside diameter of the first cable, and the second cable is more flexible than the first cable.