Abstract: An encoder includes a disc-shaped disk disposed so as to be rotatable about a rotation axis and having at least one ring-shaped track in which a rotating grating is formed and at least one fixed grating which is fixedly disposed opposed to the disk so that the fixed grating and the rotating grating construct a diffraction interference optical system. Each of a plurality of slits included in the at least one rotating grating is formed along a curved line obtained by making each of a plurality of radial lines using the rotation axis as a center curved in the circumferential direction at a predetermined curve degree so that a pitch of the slits can be set to a predetermined value.

Abstract: An encoder includes a disk including a first track and a second track each being ring-shaped and provided with a rotary grating, and a first detector and a second detector that are fixedly disposed so as to respectively face the first track and the second track each provided with a fixed grating that detects diffracted interfering light. A plurality of slits of the first track are formed as curved slits. The first detector facing the first track is disposed at a position where a tangent of each of the slits included in the diffraction grating of the first track becomes parallel to a tangent of each of the slits included in the diffraction grating of the second track at a position where the second detector faces the second track.

Abstract: An encoder includes: a main scale having two or more band-shaped tracks in each of which an optical main grating is formed so that longitudinal direction of the main scale corresponds to a measurement axis direction; and an index scale opposed to the main scale so as to form a diffraction interference optical system in cooperation with the main grating, disposed so as to be movable relative to the main scale in the measurement axis direction, and in which two or more optical index gratings are formed. A plurality of slits included in the main grating in at least one track are formed so as to be inclined at a predetermined inclination angle from a direction perpendicular to the measurement axis direction so that pitch of the slits in the track becomes equal to the pitch of the slits in the at least one other track.

Abstract: An encoder includes a slit array along a first measurement axis, and an optical module capable of relatively moving with respect to the slit array. The optical module comprises a point light source that irradiates the part of the slit array, and a light receiving array comprising a plurality of light receiving elements along a second measurement axis and arranged in positions offset with respect to the point light source. The light receiving elements is receiving light irradiated from the point light source and reflected from the reflection slit. The plurality of light receiving elements comprises respective shapes such that the light receiving element nearer to the point light source comprises a shorter length in a width direction and end parts on an opposite side of the light receiving element with respect to the point light source are arranged side by side in positions along the second measurement axis.

Abstract: An encoder includes a disk including a first track and a second track each being ring-shaped and provided with a rotary grating, and a first detector and a second detector that are fixedly disposed so as to respectively face the first track and the second track each provided with a fixed grating that detects diffracted interfering light. A plurality of slits of the first track are formed as curved slits. The first detector facing the first track is disposed at a position where a tangent of each of the slits included in the diffraction grating of the first track becomes parallel to a tangent of each of the slits included in the diffraction grating of the second track at a position where the second detector faces the second track.

Abstract: An optical entire-circumference encoder includes a plurality of rotation slits provided to transmit light at an equal pitch radially around a rotation axis as a center in a rotation track. A plurality of fixed slits is provided to transmit light at an equal pitch in a plurality of regions radially around the rotation axis as the center in a fixed track. A plurality of light receivers is disposed in a vicinity of the rotation axis to receive a light guided by the light guide in the regions respectively. The fixed slits in one of the regions and the fixed slits in another region adjacent to the one of the regions among the regions in the fixed track are formed so that a phase difference by which a rotation direction of the rotor is determined occurs between light reception signals of the plurality of light receivers.

Abstract: An encoder includes: a main scale having two or more band-shaped tracks in each of which an optical main grating is formed so that longitudinal direction of the main scale corresponds to a measurement axis direction; and an index scale opposed to the main scale so as to form a diffraction interference optical system in cooperation with the main grating, disposed so as to be movable relative to the main scale in the measurement axis direction, and in which two or more optical index gratings are formed. A plurality of slits included in the main grating in at least one track are formed so as to be inclined at a predetermined inclination angle from a direction perpendicular to the measurement axis direction so that pitch of the slits in the track becomes equal to the pitch of the slits in the at least one other track.

Abstract: An encoder includes a disc-shaped disk disposed so as to be rotatable about a rotation axis and having at least one ring-shaped track in which a rotating grating is formed and at least one fixed grating which is fixedly disposed opposed to the disk so that the fixed grating and the rotating grating construct a diffraction interference optical system. Each of a plurality of slits included in the at least one rotating grating is formed along a curved line obtained by making each of a plurality of radial lines using the rotation axis as a center curved in the circumferential direction at a predetermined curve degree so that a pitch of the slits can be set to a predetermined value.