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 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 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: 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.