By configuring an encoder scale as an angled or inclined magnet or pair of oppositely arranged, adjacent magnets, a magnetic field sensor in a travel path of the scale can detect an absolute position of the scale for use in an industrial control system. Due to the angle or incline, when a first side of the scale is proximal to the sensor, the sensor can detect an angle of 180. As the scale moves to center with respect to the sensor, the sensor can detect an increasing angle to 0. Then, as a second side of the scale becomes proximal to the sensor, the sensor can detect an increasing angle to +180. The angle changes linearly with position. In one aspect, the pair of oppositely arranged magnets can be rotated with respect to the travel path to provide the angle. In another aspect, the pair of oppositely arranged magnets can be magnetized diagonally to provide the angle.

An optical encoder is provided that can reduce the effects of unwanted diffracted light in a stable manner. The optical encoder 1 comprises a scale 2 and a detection head 3. The detection head 3 includes a light source 4 and light-receiving means 6 with a light-receiving surface 60. The light-receiving surface 60 has an element row 7 with multiple light-receiving elements 70 arranged along the measurement direction with the same period as that of the interference fringes. Here, an error included in detection signals generated from the interference fringes, with such error being caused by the fact that the number of light-receiving elements 70 is an odd number, will be referred to as a number-of-elements-induced error, and a predetermined allowable error will be referred to as an allowable error. The number of light-receiving elements 70 in the element row 7 is set to be a number where the number-of-elements-induced error is smaller than the allowable error. Such number-of-elements-induced error is caused when there is an odd total number of light-receiving elements 70 and such odd total number of light-receiving elements 70 are functional, or when there is an even total number of light-receiving elements 70 but one less than such even total number of light-receiving elements are functional.

A measurement device has: a slider which holds a substrate and is movable parallel to the XY plane; a drive system that drives the slider; a position measurement system which emits beams from a head section to a measurement surface in which grating section are provided on the slider, which receives respective return beams of the beams from the measurement surface, and which is capable of measuring position information in at least directions of three degrees of freedom including the absolute position coordinates of the slider; a mark detection system that detects a mark on the substrate; and a controller which detects the marks on the substrate using the mark detection system while controlling the drive of the slider, and which obtains the absolute position coordinates of each mark based on the detection result of each mark and measurement information by the position measurement system at the time of detection.

A method for applying a measurement scale to a guide rail surface of a linear profile rail guide, the guide rail having a first side surface and the measurement scale including at least one track extending linearly and longitudinally toward the guide rail, including several mirror regions arranged alternately one behind the other, and marking regions, uses a pulsed laser to generate a laser beam and introduces a microstructure in a first region corresponding to the at least one marking region of the first side surface. The laser generates the laser beam with a sequence of several light pulses that is directed at the first region so that the laser beam is moved two-dimensionally relative to the first region to irradiate different subregions of the first region one after the other by the light pulses. Each different irradiated subregion has an overlap with at least one other irradiated subregion.

A method for applying a measurement scale to a linear profile rail guide carriage surface, the guide carriage being guided on a guide rail linearly and longitudinally toward the guide rail and having a first side surface extending longitudinally, the measurement scale including at least one track extending linearly and longitudinally, including several mirror regions arranged alternately one behind the other, and marking regions, uses a pulsed laser to generate a laser beam and introduces a microstructure in a first region corresponding to at least one first side surface marking region. A sequence of light pulses is directed at the first region so that the laser beam is moved two-dimensionally relative to the first region to irradiate successively different subregions of the first region by the light pulses. Each different irradiated subregion has an overlap in, or transverse to, the longitudinal direction with at least two other irradiated subregions.

An encoder includes a scale having graduations arranged in a measurement direction, a head including a light receiving unit configured to receive, via the scale, light emitted from a light source, and being configured to detect a relative movement amount with respect to the scale by relatively moving in the measurement direction of the scale, and a control unit configured to control the head. The control unit includes a light amount control unit configured to perform control so as to keep a predetermined light receiving amount by increasing or decreasing a light amount of the light source, an error determination unit configured to determine an error based on light received by the light receiving unit, and a light amount suppression unit configured to suppress a light amount of the light source by stopping control performed by the light amount control unit, when the error determination unit determines as an error.

A scale attachment device configured to attach a tape scale for a linear encoder includes a fixing block and housing members. The fixing block fixes the central part of the tape scale in the lengthwise direction by pressing the central part onto a target object. The housing members include a groove to house a remaining part of the scale on both sides of the fixing block. The tape scale is inserted into the groove in the lengthwise direction with its back surface facing the bottom surface of the groove of the housing member, and thus housed in the groove. The width dimension of the opening of the groove is smaller than the width dimension of the scale.

A method is provided for operating an optical sensor unit comprising markings arranged on a piston rod of a cylinder of a n industrial truck. The method, comprises the steps of: transmitting optical radiation onto markings arranged on the piston rod receiving optical radiation reflected by the markings arranged on the piston rod detecting an oscillating voltage signal by the receiver from the optical radiation reflected by the markings on the piston rod; converting the voltage signal into a binary digital signal; setting a control current applied to the transmitter as a control variable, specifying a target voltage amplitude from the detected oscillating voltage signal as a reference variable, determining an average actual voltage amplitude over a plurality of voltage fluctuations produced by traversal of a plurality of markings from the respective actual voltage amplitudes of the voltage signals, determining a control deviation value between a target voltage amplitude and an average associated with the actual voltage amplitudes of the voltage signals, and correcting the average associated with the actual voltage amplitudes of the voltage signals by changing the control current in dependence of the control deviation value.

An encoder of a terahertz (THz)-based absolute positioning system used for decoding patterns from THz-band measurements. The encoder includes a scale with a multi-layer reflective/transmissive structure having a matrix with rows. Each row of the matrix corresponds to a plurality of patterns, such that each pattern is used to form a measurement. An emitter emits a THz waveform to the scale. A receiver is used to measure amplitudes of the THz waveform reflected from the scale. A memory stores data including predetermined positions of the emitter based on the patterns of the layers from the scale. Wherein one or more processors can determine a position of the emitter from the measurements of the amplitudes received by the receiver, based on the stored data. An output interface can be used to render the position of the emitter.

An encoder apparatus comprising a readhead moveable relative to a scale, configured to produce a position signal, as well as to produce a reference mark signal when the readhead passes over a reference mark on the scale, configured such that the process for producing the reference mark signal adapts automatically in response to a change in circumstance so as to at least pursue maintenance of a given relationship between the position and reference mark signals.