An encoder includes a scale having a continuous part where physical characteristics varies and a discontinuous part that interrupts the continuous part, a detector that be relatively displaced with respect to the scale and that detects the physical characteristics of the scale, and a processor that detects an origin of the scale on the basis of a signal for displacement detection output from the detector. The detector includes a sensitive part having sensitivity contributing to the signal for displacement detection and an insensitive part having no sensitivity contributing to the signal for displacement detection. The processor detects the origin on the basis of signal intensity of each of signals for displacement detection that the detector outputs when the sensitive and insensitive parts detect physical characteristics of the discontinuous part.

An encoder apparatus comprising a scale comprising scale features in at least one track which define a series of incremental scale marks and at least one reference mark and a readhead comprising a light source, a diffraction grating, an incremental photodetector and a reference photodetector comprising at least two detector channels. The features defining the at least one reference mark are configured such that the at least one reference mark as resolvable by each of the at least two detector channels comprises a single feature. The optical arrangement of the encoder is such that a non-imaged representation of at least the track in which the at least one reference mark is contained falls onto the detector.

An optical encoder includes a light source, a plurality of diffraction gratings including grating faces on which a plurality of grooves are disposed in parallel, and a light-receiving unit configured to receive the light diffracted at the plurality of diffraction gratings. The diffraction gratings include a first diffraction grating that is a first-stage diffraction grating adjacent to the light source, a third diffraction grating that is a last-stage diffraction grating adjacent to the light-receiving unit, and a second diffraction grating that is an output-stage diffraction grating of the first-stage diffraction grating and an input-stage diffraction grating of the last-stage diffraction grating. The diffraction gratings are disposed such that the ratio of the first gap to the third gap equals the ratio of the second gap to the fourth gap, and a length of the first gap differs from a length of the second gap.

A detection head movable relative to a scale detects diffracted light and outputs a detection result. The diffracted light is diffracted by an incremental pattern. A signal processing unit calculates a relative displacement between the scale and the detection head. The detection head includes: a light source emitting the light to the scale; and a detection unit including a light-receiving unit receiving the diffracted light through an optical element, in which the light-receiving elements outputting detection signals are periodically arranged with a predetermined period. The number of the plurality of light-receiving elements is an even number. The predetermined period is a value obtained by multiplying a fundamental period by an odd-number. The fundamental period is a period of interference fringes formed on the light-receiving unit by +1st and 1st order diffracted lights. A width of the light-receiving element is not equal to an integral multiple of the fundamental period.

An encoder including an emitter to emit a waveform to a scene including a structure. A receiver to receive the waveform reflected from the scene and to measure phases of the received waveform for a period of time. A memory to store a signal model relating phase measurements of the received waveform with phase parameters, and to store a state model relating the phase parameters with a state of the encoder. Wherein the signal model includes a motion-induced polynomial phase signal (PPS) component and a sinusoidal frequency modulated (FM) component. Wherein the PPS component is a polynomial function of the phase parameters, and wherein the FM component is a sinusoidal function of the phase parameters. A processor to determine the phase parameters using non-linear mapping of the phase measurements on the signal model and to determine the state of the encoder by submitting the phase parameters into the state model.

A linear gage includes a spindle, a guide cylinder surrounding a portion of the spindle and configured to guide the spindle to move forward and rearward in an axis line direction, and a guide slit portion having a guide slit extending parallel to the axis line of the guide cylinder, with a gap provided between the guide slit and an outer surface of the guide cylinder. An attitude adjustment pin extends into the guide slit and is fixed to a side surface of the spindle. The attitude adjustment pin is an eccentric pin.

A positioning measurement device is provided. The device includes a light source, a grating, and plural light sensors. A periodic light field is generated by light emitted by the light source and passes through the grating to. The plural light sensors are periodically spaced. The light sensors are used to sense the periodic light field for generating a plurality of positioning measurement signals.

A length-measuring device includes a scanning carriage for scanning a measuring graduation that is to be guided longitudinally in the measurement direction on a guide surface. A coupling couples the scanning carriage to a drive dog rigidly in the measurement direction and resiliently transversely to the measurement direction. A first spring is disposed between a connecting element of the coupling and the drive dog and exerts a pressure force on the scanning carriage at a first position so as to press the scanning carriage against the guide surface. A second spring is disposed between the connecting element and the scanning carriage. The second spring is spaced apart from the first spring in the measurement direction and exerts a pressure force on the scanning carriage at a second position spaced apart from the first position in the measurement direction so as to press the scanning carriage against the guide surface.

A scale includes a substrate, a metal layer of Ni formed on one principal surface of the substrate, and a scale grating formed on the metal layer. A plurality of gratings of Cr are disposed at a predetermined interval in the scale grating.

An encoder apparatus including a readhead for reading a reflective scale located adjacent the readhead. The readhead includes a circuit board on which a sensor including one or more photodiodes for detecting light reflected from a scale located adjacent the readhead is mounted, and at least one light emitting element. The light emitting element is mounted to the circuit board via a light emitting element support structure which holds the light emitting element away from the circuit board and the sensing plane of the sensor, and at least a part of which extends over the sensor.