Abstract: A method and apparatus are described for forming a pattern including one or more markings on a substrate. The method includes the step of forming each marking by locally heating the substrate, for example using a fibre laser. A step is also performed of monitoring the temperature of the substrate, e.g. using a temperature sensor, whilst each marking is being formed. The method may be used to form a magnetic encoder scale on a stainless steel substrate having a high content of martensitic material. The local heating causes the martensitic material to be transformed into austenitic material. An encoder scale made using the method is also described.

Abstract: The present invention relates to a method for producing a magnetic substrate for an encoder scale. The method comprising the step of mechanically working the substrate, wherein the substrate is cooled prior to the mechanical working step. In one embodiment, a stainless steel substrate is used. The stainless steel may comprise an austenite (non-magnetic) phase and a martensite (magnetic) phase. Mechanically working and cooling in this manner increases the amount of magnetic (martensite) phase material that is formed, thereby improving the magnetic contrast when non-magnetic (austenite) marking are subsequently formed on the substrate by laser marking.

Abstract: A readhead is provided for reading an absolute scale, optionally a passive magnetic scale, that encodes a series of data bits. The readhead includes a plurality of sensors, such as an array of Hall sensors, for producing a plurality of sensor signals. A plurality of signal combiners are also provided to receive at least two of the sensor signals and produce therefrom a combined sensor signal. A plurality of data bit extractors are arranged to receive at least two combined sensor signals and to determine the value of a data bit encoded in an associated absolute scale. The readhead also comprises an incremental signal generator for generating at least one incremental signal from the combined sensor signals produced by a plurality of the signal combiners. In this manner, both absolute and incremental position is measured.

Abstract: The invention relates to the process and device for adjusting a rotary encoder, i.e. the absolute magnetic rotary encoder with Hall effect sensors which, when positioned in the form of a circle, detect the magnetic field of a diametrically polarised permanent magnet. The rotary encoder adjustment process features the following: the actuator magnet turns once or several times over the sensor circuit, whereby the time-dependant rotation angle is recorded/stored; time-dependant presupposed values of the rotation angle are calculated; these are then subtracted from the measured actual rotation angle values; by analysing the obtained difference, the electric parameter values for the sensor circuit are determined in such a manner as to make the newly measured difference based on new electric parameter values smaller than before the change; the electric parameter values for the sensor circuit are written into the sensor circuit.

Abstract: A magnetic encoder apparatus is presented that includes a plurality of magnetic sensor elements (e.g. Hall sensors) for reading an associated magnetic scale that produces a periodically repeating magnetic pattern. The plurality of magnetic sensor elements produce a plurality of sensor signals and an analyzer is provided for analyzing the plurality of sensor signals to provide a measure of the position of the magnetic sensor elements relative to the associated magnetic scale. The analyzer is arranged to use the plurality of sensor signals to assess the period of the periodically repeating magnetic pattern sensed by the plurality of magnetic sensor elements. In this manner, the requirement to carefully match the period of the sensor elements with the periodically repeating magnetic pattern of the associated magnetic scale is avoided.

Abstract: The present invention relates to an encoder readhead. The readhead includes a housing having an opening for capturing an encoder scale including an elongate rod having a substantially circular cross-section, the opening defining an axial direction along which a captured encoder scale can slide back and forth. A scale reader, which may include an array of Hall sensors, is provided for reading a portion of an encoder scale located in the opening. The housing includes an access portion that allows the encoder scale to be inserted into, and/or removed from, the opening by a relative movement between the housing and the encoder scale in a direction other than the axial direction.

Abstract: A scanning device for a position encoder is provided that comprises a plurality of sensor elements for generating a plurality of sensor signals. A summation unit is also provided for generating at least a first summation signal and a second summation signal that provide information on the relative alignment of the scanning device and an associated scale. The first summation signal is generated from a first subset of the plurality of sensor signals and the second summation signal is generated from a second subset of the plurality of sensor signals. The plurality of sensor elements are substantially evenly spaced apart from one another N and sensor elements are provided per period of an associated scale, wherein N is an integer value and a multiple of three and four. In this manner, the third harmonic contribution to the summation signals is suppressed.

Abstract: A magnetic scale includes a scale member having a plurality of grooves. The scale member defines a passive magnetic scale track. The plurality of grooves include grooves of at least a first groove type and a second groove type, the magnetic properties of the scale member in the locality of grooves of the first groove type being different than the magnetic properties of the scale member in the locality of grooves of the second groove type. The scale member is arranged to carry or encode absolute position information in the form of at least one codeword comprising a sequence of data bits, wherein each of the data bits is provided by a groove of the scale member, the data bit taking a first value if the groove is of the first groove type and a second value if the groove is of the second groove type.

Abstract: A method and apparatus are described for forming a pattern including one or more markings on a substrate. The method includes the step of forming each marking by locally heating the substrate, for example using a fibre laser. A step is also performed of monitoring the temperature of the substrate, e.g. using a temperature sensor, whilst each marking is being formed. The method may be used to form a magnetic encoder scale on a stainless steel substrate having a high content of martensitic material. The local heating causes the martensitic material to be transformed into austenitic material. An encoder scale made using the method is also described.

Abstract: The present invention relates to a method for producing a magnetic substrate for an encoder scale. The method comprising the step of mechanically working the substrate, wherein the substrate is cooled prior to the mechanical working step. In one embodiment, a stainless steel substrate is used. The stainless steel may comprise an austenite (non-magnetic) phase and a martensite (magnetic) phase. Mechanically working and cooling in this manner increases the amount of magnetic (martensite) phase material that is formed, thereby improving the magnetic contrast when non-magnetic (austenite) marking are subsequently formed on the substrate by laser marking.

Abstract: The present invention relates to an encoder readhead. The readhead includes a housing having an opening for capturing an encoder scale including an elongate rod having a substantially circular cross-section, the opening defining an axial direction along which a captured encoder scale can slide back and forth. A scale reader, which may include an array of Hall sensors, is provided for reading a portion of an encoder scale located in the opening. The housing includes an access portion that allows the encoder scale to be inserted into, and/or removed from, the opening by a relative movement between the housing and the encoder scale in a direction other than the axial direction.

Abstract: A magnetic encoder scale having a series of periodically spaced magnetic marks. A reference mark is applied to the scale using an applicator or template, which has a feature for locating the reference mark. The applicator or template has one or more magnetic marks corresponding to the periodic scale marks, whereby the applicator or template automatically assumes a defined phase relationship relative to the periodic scale marks when placed on the scale. The reference mark may be attached to the scale self-adhesively, or it may be formed by removal of material from the scale, guided by the applicator or template. The applicator may alternatively have a strong permanent magnet which applies further magnetization to a region of the scale.

Abstract: A scanning device for a position encoder is provided that comprises a plurality of sensor elements for generating a plurality of sensor signals. A summation unit is also provided for generating at least a first summation signal and a second summation signal that provide information on the relative alignment of the scanning device and an associated scale. The first summation signal is generated from a first subset of the plurality of sensor signals and the second summation signal is generated from a second subset of the plurality of sensor signals. The plurality of sensor elements are substantially evenly spaced apart from one another N and sensor elements are provided per period of an associated scale, wherein N is an integer value and a multiple of three and four. In this manner, the third harmonic contribution to the summation signals is suppressed.

Abstract: A readhead is provided for reading an absolute scale, optionally a passive magnetic scale, that encodes a series of data bits. The readhead includes a plurality of sensors, such as an array of Hall sensors, for producing a plurality of sensor signals. A plurality of signal combiners are also provided to receive at least two of the sensor signals and produce therefrom a combined sensor signal. A plurality of data bit extractors are arranged to receive at least two combined sensor signals and to determine the value of a data bit encoded in an associated absolute scale. The readhead also comprises an incremental signal generator for generating at least one incremental signal from the combined sensor signals produced by a plurality of the signal combiners. In this manner, both absolute and incremental position is measured.

Abstract: A magnetic scale includes a scale member having a plurality of grooves. The scale member defines a passive magnetic scale track. The plurality of grooves include grooves of at least a first groove type and a second groove type, the magnetic properties of the scale member in the locality of grooves of the first groove type being different than the magnetic properties of the scale member in the locality of grooves of the second groove type. The scale member is arranged to carry or encode absolute position information in the form of at least one codeword comprising a sequence of data bits, wherein each of the data bits is provided by a groove of the scale member, the data bit taking a first value if the groove is of the first groove type and a second value if the groove is of the second groove type.

Abstract: A magnetic encoder scale comprises a series of periodically spaced magnetic marks. A reference mark is applied to the scale using an applicator or template, which has a feature for locating the reference mark. The applicator or template comprises one or more magnetic marks corresponding to the periodic scale marks, whereby the applicator or template automatically assumes a defined phase relationship relative to the periodic scale marks when placed on the scale. The reference mark may be attached to the scale self-adhesively. Or it may be formed by removal of material from the scale, guided by the applicator or template. Or the applicator may comprise a strong permanent magnet which applies further magnetisation to a region of the scale.